CN110163945B - Water surface simulation method in real-time rendering - Google Patents

Abstract

The invention relates to a method for water surface simulation in real-time rendering, belongs to the field of computer graphics, and aims to solve the problem that the existing real-time rendering simulation technology of water surface cannot give consideration to both realism and calculation efficiency. The present invention mainly includes seven algorithm modules or parts, namely: reflection camera, slice normal generation module, water surface reflection color generation module, underwater color generation module, Fresnel coefficient generation method, highlight reflection color generation method, water surface color mixing method. The present invention can obtain the final water surface effect through the cooperation of the above algorithm modules or parts. The present invention can be applied to mainstream real-time three-dimensional programming interface: OpenGL or DirectX. In addition, the method adopted in the present invention can give consideration to both realism and computational efficiency in a three-dimensional interactive application that does not involve physical simulation of the water body itself and does not involve observation under the water surface.

Description

A Water Surface Simulation Method in Real-time Rendering

technical field

The invention relates to a water surface simulation method in real-time rendering, which belongs to the field of real-time rendering of computer graphics and is applied to video games, interactive art, real-time 3D environment simulation or scene design industries.

Background technique

In recent years, with the development of hardware equipment and the entertainment industry, people have paid more and more attention to the 3D display effect, among which the 3D display effect obtained by real-time rendering is particularly eye-catching. In real-time rendered 3D scenes, water surface effects have a wide range of application scenarios. As long as it involves the simulation of daily life or natural scenes, it will inevitably involve the simulation of water surface effects.

For ease of understanding, here is a brief introduction to the basics of graphics. We take the high-level shader language (HLSL) as an example to briefly introduce the rendering pipeline and space transformation. First, high-level shader languages allow us to use programmable graphics hardware, allowing us to control the shape, appearance and movement of objects. A pipeline is a series of steps executed in parallel and in a fixed order. Each step receives input from the previous step and outputs results to the next immediately following step. Just like an assembly line, there are many cars being manufactured and assembled at the same time, but they are in different stages of the same line. Overall, a rendering pipeline is fed a description of a 3D scene and a virtual camera with orientation and position. This rendering pipeline can only be the entire process of converting what the camera sees into a 2D image. In this method, only the programming for the vertex shader stage and the fragment shader stage is involved. For example, the vertex shader, after the basic geometric primitives are assembled, these vertices will be given to the vertex shader stage. A vertex shader can be thought of as a function whose input is a vertex and whose output is also a vertex. Every vertex that needs to be drawn flows through this vertex shader. Another example is the fragment shader. A fragment shader will be executed once for each pixel fragment, and it will use the interpolated vertex attributes as input data to calculate the color. A pixel shader can be as simple as attaching a fixed color. Of course, it can also be very complex, such as to calculate the lighting, reflection and shadow effects per pixel.

Next, we introduce the basic concepts of spatial transformations involved in the graphics pipeline. In general, mapping a 3D scene to 2D requires several spaces and transformations. Model space, world space, view space, clip space, and screen space. The transformation from model space to world space is called model transformation, the transformation from world space to observation space is called observation transformation, the transformation from observation space to clipping space is called projection transformation, and the transformation from clipping space to screen space is called screen mapping.

There are often two extremes in the existing water surface simulation technology. One type pays more attention to the scientific nature of water body movement, such as how the top of the water surface moves under the influence of wind force, underwater force, etc., and then scientifically expresses the effect of water surface ripples; There are two main problems in one type of water surface simulation. The first problem is that this type of technology often ignores other effects that can also significantly enhance the reality of the water surface, such as: reflection of the surrounding environment on the water surface, high light on the water surface, refraction of the underwater environment, Fresnel phenomenon, etc.; the second problem lies in its relatively large amount of calculation, because it changes the position of each vertex of the water surface and combines the diffuse reflection model to obtain the ripple effect of the water surface, which will significantly increase the number of basic primitives that need to be drawn. This in turn increases the burden on the graphics card; in addition, since the vertex position is calculated based on dynamic physical parameters, it also significantly increases the computational burden on the CPU. To sum up, this kind of effects are often rendered on professional graphics workstations, and they are difficult to apply on home desktops, laptops, or mobile devices.

Another type of water surface simulation technology pays more attention to computing efficiency. This type of effect is more focused on how to run on all devices, so some water surface effects are generally discarded, such as: Fresnel effect, specular model and even environmental reflection. However, with the development of hardware and the theory of simplified Fresnel calculation formulas and simplified highlight models, these theories should also be applied to these water surface simulation technologies to increase the realism of the water surface.

Contents of the invention

In view of the above-mentioned problems in the prior art, the purpose of the present invention is to provide a real-time water surface simulation technology that can take into account both computational efficiency and realism, which aims to solve the problem that the current water surface simulation technology cannot take into account these two characteristics.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A water surface rendering process based on OpenGL or DirectX image application programming interface. From a macro perspective, it consists of two steps, namely: the reflection camera acquires the scene reflection image, the main camera renders the scene image containing the water surface; and seven algorithm modules or parts, namely: the reflection camera, the fragment normal generation module, and the reflection color of the water surface Generation module, underwater color generation module, Fresnel coefficient generation method, specular reflection color generation method, water surface color mixing method.

Further, the first macroscopic step can be divided into the following eight steps, 8 of which are automatically processed by the image application programming interface, as shown in Figure 2:

1) Create a reflection camera. This step is to completely duplicate the main camera, as a reflection camera. The meaning of full copy is to copy the position and orientation data of the main camera to the newly created reflection camera;

2) Obtain the reflection matrix about the water surface plane. In this step, input the four-dimensional vector representation of the water surface plane in the world space, and calculate the reflection matrix about the water surface plane in the world space according to the mirror reflection principle of linear algebra;

3) Obtain the observation transformation matrix of the current reflection camera;

4) The reflection matrix is right multiplied by the observation transformation matrix;

5) Replace the observation transformation matrix of the current reflection camera with the matrix obtained in step 4. The result obtained in this step is equivalent to making the vertices of all objects perform a mirror transformation on the water plane before converting from the world space to the camera observation space;

6) Transform the four-dimensional vector representing the current water plane from the world space to the observation space of the reflection camera. For specific principles, please refer to the space transformation in linear algebra;

7) Use the four-dimensional vector of the water surface plane obtained in step 6 as the near clipping plane, and modify the projection matrix of the reflection camera. For specific methods and principles, please refer to Chapter 2, Section 2.6 of "The Essence of Game Programming 5";

8) The reflection camera renders the scene in the viewing frustum as a reflection image of the water plane. The graphical programming interface automatically accesses the reflection camera's projection matrix and automates the process;

Further, the second macro step can be divided into the following seven steps, wherein 2, 5, and 7 are automatically processed by the graphics application programming interface. 4 and 6 are programmed by the engineer and automatically called by the graphic application programming interface, see Figure 3:

1) Set the rendering order of the water plane so that it is rendered after other objects in the scene;

2) According to the rendering order, render the objects before the water plane into the final image;

3) Associate the two-dimensional image rendered by the previous reflection camera with the water surface. That is: it allows us to access and store the two-dimensional image data rendered by the reflection camera through the water surface object;

4) Input the data of one step on the rendering pipeline, process it with the water surface vertex shader, and output the generated data to the next step; Information, obtain the position of each point in the water surface in the clipping space of the main camera, the position in the world space, the tangent vector corresponding to the vertex in the world space, the subtangent vector corresponding to the vertex in the world space, and the corresponding vertex in the world space The normal vector of the vertex, the screen position corresponding to the vertex, and the normal texture coordinates corresponding to the vertex;

5) Primitive assembly, rasterization and interpolation;

6) Input the data of one step on the rendering pipeline, process it with the water surface fragment shader, and output the generated data to the next step. In this step, the color and depth information of each water plane fragment is obtained according to the previously obtained information through the fragment shader of the water plane;

7) Update the pixel corresponding to the position of the water surface in the image rendered by the main camera;

Further, the sixth step of the second macro-step can be divided into the following six steps. The dependencies between the steps are shown in Figure 4. As long as the dependencies are met, the order of the steps can be exchanged at will:

1) Input the required data to the fragment normal generation module to obtain the normal vector of the current fragment in tangent space or world space. For specific explanation, please refer to the description of the module below;

2) Input the required data to the underwater color generation module to obtain the underwater refraction color corresponding to the current fragment. For specific explanation, please refer to the description of the module below;

3) Input the required data to the water surface reflection color generation module to obtain the water surface reflection color corresponding to the current fragment. For specific explanation, please refer to the description of the module below;

4) Obtain the dot product of the view direction and the normal vector in the world space corresponding to the current fragment. Use the Fresnel simplified formula method described below to obtain the Fresnel coefficient corresponding to the current fragment. The viewing angle direction can be obtained by accessing the corresponding built-in parameters of the camera;

5) Use the Phong highlight reflection method for the light reflection direction, highlight color, viewing angle direction and smoothness coefficient corresponding to the current fragment to obtain the highlight reflection color corresponding to the current fragment; where the light reflection direction can be determined by the world space method The line vector and the incident direction of the light are calculated by reflection. The incident direction of light can be obtained directly through the graphical programming interface. The highlight color and smoothness coefficient are set by the user, which is convenient for adjusting the final effect in time. The method of obtaining the viewing angle direction is the same as step 4. See below for the Phong specular reflection method;

6) Calculate the underwater refraction color obtained in step 2, the water surface reflection color obtained in step 3, the Fresnel coefficient obtained in step 4, and the highlight reflection color obtained in step 5 to obtain the final color corresponding to the fragment. In this step, the specific calculation method is:

Water surface reflection color × Fresnel coefficient + underwater refraction color × (1-Fresnel coefficient) + specular reflection color

= The final color corresponding to the fragment

Furthermore, the input data, operation steps and generated results required by the fragment normal generation module are as follows. First of all, the data required by this module are: the normal texture of the water surface ripple, the normal texture coordinates corresponding to the fragment, the tangent vector corresponding to the fragment in the world space, the subtangent vector corresponding to the fragment in the world space, The normal vector and time variable corresponding to the fragment in the world space, the sampling interval along the X-axis direction of the texture and the sampling interval along the Y-axis direction of the texture input by the user. Next, for the operation steps:

1) Use the user-input sampling interval along the X-axis direction of the texture and the sampling interval along the Y-axis direction of the texture to form a two-dimensional vector;

2) multiply the two-dimensional vector obtained in step 1 by the time variable to obtain the sampling interval;

3) Add the sampling interval obtained in step 2 to the normal texture coordinate corresponding to the fragment to obtain the first sampling position;

4) Subtract the sampling interval obtained in step 2 from the normal texture coordinate corresponding to the fragment to obtain the second sampling position;

5) Use the sampling position obtained in step 3 to sample the normal texture of the water surface ripples to obtain a color value, and then map the color value to a normal vector in the tangent space. The mapping principle is well known, please refer to Section 7.2.2 of "Introduction to Unity Shader";

6) Use the sampling position obtained in step 4 to sample the normal texture of the water surface ripples to obtain a color value, and then map the color value to a normal vector in the tangent space. The mapping principle is well known, please refer to Section 7.2.2 of "Introduction to Unity Shader";

7) Add the normal vectors in the tangent space obtained in steps 5 and 6 and normalize them to a unit vector to obtain the normal vector sampled in the final tangent space. The standardization process is well known, please refer to the related information of linear algebra;

8) Combine the tangent vector corresponding to the fragment in the world space, the subtangent vector corresponding to the fragment in the world space, and the normal vector corresponding to the fragment in the world space into a matrix, which can transform the vector in the tangent space into world space. The specific combination method is well known, please refer to Section 4.6.2 of "Introduction to Unity Shader";

9) multiply the matrix obtained in step 8 by the normal vector in the tangent space obtained in step 7 to obtain the normal vector in the world space corresponding to the fragment;

In general, the module finally outputs the normal vector in tangent space and the normal vector in world space corresponding to the fragment.

Further, the input data, operation steps and generated results required by the underwater color generation module are as follows. First of all, the data required by this module are: the normal vector in the tangent space of the fragment, the distortion coefficient (obtained by the user), and the final image obtained in the second step of the second macro step except the water surface itself The scene image of , the screen space position of the current water fragment in the main camera, and the pixel size of the scene image except the water itself. Next, for the operation steps:

1) The two-dimensional vector composed of the x and y components of the normal vector in the tangent space of the fragment, the distortion coefficient (obtained by the user), and the x and y components of the pixel size of the scene image except the water surface itself The two-dimensional vectors are multiplied correspondingly to obtain the offset vector;

2) Multiply the offset vector obtained in step 1 by the z component of the current water surface fragment in the screen space position of the main camera, plus the x and y components corresponding to the current water surface fragment in the screen space position of the main camera 2D vector gets a 2D vector;

3) divide the two-dimensional vector obtained in step 2 by the w component of the current water surface fragment in the screen space position of the main camera, to obtain a two-dimensional vector;

4) Use the two-dimensional vector to sample the scene image except the water surface itself, to obtain the underwater refraction color corresponding to the fragment;

Overall, the module finally outputs the corresponding underwater refraction color for that fragment.

Further, the input data, operation steps and generated results required by the water surface reflection color generation module are as follows. First, the data required by this module are: the corresponding normal direction of the fragment in the world space, the reflection image of the water plane, and the corresponding position of the fragment in the main camera screen space. Next, for the operation steps:

1) Use the position corresponding to the fragment in the screen space of the main camera plus the normal direction corresponding to the fragment in the world space to obtain a two-dimensional vector;

2) Sampling the reflection image of the water surface plane with the two-dimensional vector to obtain the reflection color corresponding to the fragment;

3) In general, the fragment finally outputs the water reflection color corresponding to the fragment.

Further, the following is a simplified Fresnel formula to generate the Fresnel coefficient corresponding to the fragment. Among them, f _λ is set to 0, and u represents the dot product of the view direction and the normal vector corresponding to the current fragment.

F _λ (u)=f _λ +(1-f _λ )(1-u) ⁵

为光的反射方向，它通过光相对于片元的方向和当前片元对应的法线向量得出；

为视角方向；m_gloss为光滑度系数，取值为22；m_specular为高光反射颜色；c_light为光照颜色。Further, the following is the Phong specular reflection formula, which calculates the specular color corresponding to the fragment. in

is the reflection direction of the light, which is obtained by the direction of the light relative to the fragment and the normal vector corresponding to the current fragment;

is the viewing angle direction; m _gloss is the smoothness coefficient, the value is 22; m _specular is the specular reflection color; c _light is the light color.

The following code is the implementation of this formula in Cg/HLSL for reference.

fixed3 specular = _LightColor0.rgb*_Specular.rgb*pow(saturate(dot(myLightReflectDir, myviewDir)), _Gloss);

Further, the water surface color mixing module can generate the final color of the water surface. This module mixes the reflection color and refraction color according to the Fresnel coefficient to generate the initial water surface color corresponding to the fragment. In this step, the specific calculation method is:

Water surface reflection color × Fresnel coefficient + water surface refraction color × (1-Fresnel coefficient) + specular reflection color

= The final color corresponding to the fragment

Three algorithm modules and four methods or partial dependencies included in the present invention are shown in FIG. 6 . The water surface reflection color generation module depends on the reflection camera and the fragment normal generation module; the underwater color generation module and Fresnel coefficient generation method depend on the fragment normal generation module; the water surface color mixing method depends on the water surface reflection color generation module and the bottom color Generation module and Fresnel coefficient generation method; the final color mixing method of the water surface depends on the water surface reflection color generation module, underwater color generation module, Fresnel coefficient generation method and specular reflection color generation method.

Compared with prior art, the beneficial effect of the present invention:

1) The present invention can improve the realism of the water surface in real-time rendering, see the comparison between FIGS. 7, 8, 9, and 10. From the perspective of the overall effect, the water surface effect of this project is better than the two official effects for example. Specifically reflected in the addition of high-light reflections on the water surface, more obvious wave effects, and more obvious and adjustable Fresnel effects. For specific analysis, please refer to the description of the relevant drawings below.

2) The present invention can run smoothly on the current mainstream personal consumer devices. For specific analysis, please refer to the description of the related drawings below.

For detailed data explanation, please refer to the description of Figures 7-13 after the description of the figures.

Description of drawings

Fig. 1 is an overall rendering flow chart of the present invention.

Fig. 2 is a flowchart of acquisition of reflection images by the reflection camera of the present invention.

Fig. 3 is a flow chart of the rendering of the water surface in the main camera of the present invention.

FIG. 4 is a flow chart of generating fragments by the fragment shader of the water surface plane in the main camera of the present invention.

FIG. 5 is a structural diagram of the relationship between modules or methods in the fragment shader of the present invention.

Fig. 6 is a structural diagram of all modules or methods of the present invention.

Figure 7 Unity's official second-generation water surface shader renderings and test results.

Fig. 8 is an effect diagram and test results of the water surface simulation method of the present invention.

Fig. 9 is the effect diagram 2 of the water surface simulation method of the present invention.

Figure 10 Unity's official fourth-generation water surface shader renderings and test results.

Figure 11 The test results of Unity's official second-generation water surface in Unity Profiler.

Fig. 12 is the test result of the water surface simulation method of the present invention in Unity Profiler.

Figure 13 The test results of Unity's official fourth-generation water surface in Unity Profiler.

Figure 14 is an organizational structure based on the Unity platform.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and examples of implementation. It should be understood that the specific implementation cases described here are only used to explain the present invention, not to limit the present invention.

First of all, combined with Figures 1, 2, 3, 4 and their explanations in the summary of the invention, engineers in the field should be able to use various languages or platforms to construct water surface effects relatively clearly. Here, in order to make the implementation more clear, the present invention will further illustrate the implementation of the present invention according to the code organization chart of the actual case under the Unity platform.

Figure 14 illustrates an organizational structure based on the Unity platform. Among them, the water surface plane is an object in Unity, and the water surface special effect C# script and the water surface special effect Unity Shader will be mounted.

Among them, under the Unity platform, C# mainly controls the CPU. The main function of the C# script here is to obtain the resources provided by the Unity platform and some information contained in the water plane, and control the CPU to calculate the reflection image of the water plane and send it to the water surface special effect Unity Shader.

For the water surface effect Unity Shader, its main object is the GPU. Its main function here is to control the GPU so that it can calculate the final effect of the entire water surface through Unity using various resources provided by the Unity platform, the reflection image from the water surface special effect C# script, and the information contained in the water surface itself. Transfer to the screen to form an image of the entire water surface.

In the following, Figures 7-13 will be explained in detail to support the conclusions involved in the beneficial effects.

The first is an explanation of the effect. Due to the artistry of simulation, when we compare the realism, we often incorporate subjective judgments. So, here, we only make comparisons based on the quantity and quality of simulated natural phenomena involved in the water surface. From Figure 7, we can see reflection, refraction, water ripples, and Fresnel effects. We can find that because the ripples on the water surface will produce a large number of brown areas, the water surface appears to be very messy, which affects our observation of the Fresnel effect. From Figs. 8 and 9, we can see that the water surface simulation effects of the present invention include reflection, refraction, water surface ripple, Fresnel effect and specular reflection. Compared with Figure 7, at least it will not look very trivial, and the waves are more natural; the high light reflection can also make people notice the sunlight in the environment. In addition, because there is no influence of messy waves, the Fresnel effect is also more obvious; we can see the near bottom of the water more easily, but it is difficult to see the bottom of the distant water (this is the simulation of the Fresnel effect). From Figure 10, what we see is a relatively smooth water surface. From this water surface, we can see refraction, reflection, water surface ripples and Fresnel effects. But after comparing with this project, we will find that its Fresnel effect is weak. And it is difficult to adjust, because the Fresnel coefficient of a certain position on the official water surface of Unity is mostly obtained according to the sampling of the image texture, rather than calculated in real time through the simplified Fresnel formula.

In addition to the effect, this project also compared the performance of each water surface in the same scene. The test environment for this test is CPU: Intel Core i7-8750H, RAM: 16.0GB, GPU: NVIDIA GTX1060 3GB Max-Q. The specific results are as follows: Among them, the three more important indicators are CPU Usage, GPU Usage and the frame rate behind Graphics. Among them, the smoothness of a picture is determined by both the CPU and the GPU. Because the CPU is responsible for collecting three-dimensional or two-dimensional data, and the GPU is responsible for rendering these data into two-dimensional images with a three-dimensional effect. Among them, the specific meaning of the Rendering component in the CPU Usage is the time taken by the CPU to collect the data and commands that need to be rendered. This component and the various components of the GPU together determine the rendering speed. In addition, the Graphics frame rate in Statistics can be seen as the final result of rendering, that is, the number of images drawn per second. In theory, for most games, when the frame rate reaches 30 frames or more, people will feel that the game is smooth.

Through comparison, we can find that the water surface of this project is also better than the two official water surfaces given by Unity in terms of performance. First of all, from an overall point of view, the frame rate of Unity’s official second-generation water surface is always maintained at around 120 frames; the frame rate of this project’s water surface is maintained at around 130 frames; and the frame rate of Unity’s official fourth-generation water surface is maintained at around 100 frames. From the perspective of CPU resource allocation, Unity's official water consumption is more in the performance of vertical synchronization. This function is mainly to synchronize the refresh of the display with the work of the graphics card to avoid tearing the screen. The water surface of this project is mainly the process of script processing and collecting the information required for rendering that consumes CPU resources. In addition, in terms of GPU consumption, in general, these three special effects are similar. However, this water surface makes GPU resources mainly consumed in post-processing, while the other two water surfaces make GPU resources mainly consumed in other problems.

The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention are all Should be covered within the protection scope of the present invention.

Claims (6)

1. A water surface simulation method in real-time rendering, characterized in that, comprises two macroscopic steps, namely: the reflection camera obtains the scene reflection image step, and the main camera renders the step of including the scene image of the water surface, The first macro step can be divided into the following eight steps, of which 8) is automatically handled by the image application programming interface: 1) Create a reflection camera, which is used to completely copy the main camera as a reflection camera; 2) Obtain the reflection matrix about the water surface plane, specifically: this step inputs the four-dimensional vector representation of the water surface plane in the world space, and calculates the reflection matrix about the water surface plane in the world space according to the specular reflection principle of linear algebra; 3) Obtain the observation transformation matrix of the current reflection camera; 4) The reflection matrix is right multiplied by the observation transformation matrix; 5) Substitute the observation transformation matrix of the current reflection camera with the matrix obtained in step 4; 6) Transform the four-dimensional vector representing the current water surface plane from the world space to the observation space of the reflection camera; 7) modify the projection matrix of the reflection camera with the obtained plane four-dimensional vector as the near clipping plane; 8) The reflection camera renders the scene in the frustum into a reflection image of the water plane; The second macroscopic step can be divided into the following seven steps, wherein 2, 5, and 7 are automatically processed by the graphical application programming interface; 4, 6 is programmed by the engineer himself and automatically called by the graphical application programming interface; 1) Set the rendering order of the water plane so that it is rendered after other objects in the scene; 2) According to the rendering order, render the objects before the water plane into the final image; 3) Associating the two-dimensional image rendered at this time with the water surface; 4) Input the data of one step on the rendering pipeline, perform water surface vertex shader processing, and output the generated data to the next step; 5) Primitive assembly, rasterization and interpolation; 6) Input the data of one step on the rendering pipeline, process it with the water surface fragment shader, and output the generated data to the next step; 7) Updating the pixel corresponding to the position of the water surface in the image rendered by the main camera. 2. the water surface simulation method in the real-time rendering according to claim 1, is characterized in that, the 6th step of the second macro step is divided into the following six steps, as long as it meets the dependency relationship, the order between the steps can be exchanged at will: 1) Input the required data to the fragment normal generation module to obtain the normal vector of the current fragment in the tangent space and the world space; 2) Input the required data to the underwater color generation module to obtain the underwater refraction color corresponding to the current fragment; 3) Input the required data to the water surface reflection color generation module to obtain the water surface reflection color corresponding to the current fragment; 4) Obtain the dot product of the viewing angle direction and the normal vector in the world space corresponding to the current fragment, and use the Fresnel simplified formula method for the dot product to obtain the Fresnel coefficient corresponding to the current fragment; 5) Use the Phong highlight reflection method for the light reflection direction, highlight color, viewing angle direction and smoothness coefficient corresponding to the current fragment to obtain the highlight reflection color corresponding to the current fragment; 6) Calculate the underwater refraction color obtained in step 2, the water surface reflection color obtained in step 3, the Fresnel coefficient obtained in step 4, and the highlight reflection color obtained in step 5 to obtain the final color corresponding to the fragment, and calculate in detail The formula is as follows: Water surface reflection color × Fresnel coefficient + underwater refraction color × (1-Fresnel coefficient) + highlight reflection color = final color corresponding to this fragment. 3. The water surface simulation method in real-time rendering according to claim 1, wherein the reflection camera can generate reflection images. 4. the water surface simulation method in the real-time rendering according to claim 2, is characterized in that, the required input data, operation steps and the result of generation of described fragment normal line generation module are specifically as follows: The data required by this module are: the normal texture of the water surface ripple, the normal texture coordinates corresponding to the fragment, the tangent vector corresponding to the fragment in the world space, the subtangent vector corresponding to the fragment in the world space, and the world space The normal vector and time variable corresponding to the fragment, the sampling interval along the X-axis direction of the texture and the sampling interval along the Y-axis direction of the texture input by the user; Next, for the operation steps: 1) Use the user-input sampling interval along the X-axis direction of the texture and the sampling interval along the Y-axis direction of the texture to form a two-dimensional vector; 2) multiply the two-dimensional vector obtained in step 1 by the time variable to obtain the sampling interval; 3) Add the sampling interval obtained in step 2 to the normal texture coordinate corresponding to the fragment to obtain the first sampling position; 4) Subtract the sampling interval obtained in step 2 from the normal texture coordinate corresponding to the fragment to obtain the second sampling position; 5) Sampling the normal texture of the water surface ripple with the sampling position obtained in step 3 to obtain a color value, and then map the color value to a normal vector in tangent space; 6) Sampling the normal texture of the water surface ripple with the sampling position obtained in step 4 to obtain a color value, and then map the color value to a normal vector in tangent space; 7) adding and normalizing the normal vectors in the tangent space obtained in steps 5 and 6 to a unit vector to obtain the normal vector sampled in the final tangent space; 8) Combine the tangent vector corresponding to the fragment in the world space, the subtangent vector corresponding to the fragment in the world space, and the normal vector corresponding to the fragment in the world space into a matrix, which can transform the vector in the tangent space into world space; 9) multiply the matrix obtained in step 8 by the normal vector in the tangent space obtained in step 7 to obtain the normal vector in the world space corresponding to the fragment; Finally, the normal vector in the tangent space and the normal vector in the world space corresponding to the fragment are output. 5. the water surface simulation method in the real-time rendering according to claim 2, is characterized in that, the required input data, operation steps and the result of generation of described underwater color generation module are specifically as follows: The data required by this module are: the normal vector in the tangent space of the fragment, the distortion coefficient, the scene image in the final image obtained in step 2 of the second macroscopic step except the water surface itself, and the current water surface fragment the screen-space position of the main camera, and the pixel size of the scene image except for the water itself; Next, for the operation steps: 1) Multiply the two-dimensional vector composed of the x and y components of the normal vector in the fragment tangent space, the distortion coefficient, and the x and y components of the pixel size of the scene image except the water surface itself , get the offset vector; 2) Multiply the offset vector obtained in step 1 by the z component of the current water surface fragment in the screen space position of the main camera, plus the x and y components corresponding to the current water surface fragment in the screen space position of the main camera 2D vector gets a 2D vector; 3) divide the two-dimensional vector obtained in step 2 by the w component of the current water surface fragment in the screen space position of the main camera, to obtain a two-dimensional vector; 4) Use the two-dimensional vector to sample the scene image except the water surface itself, to obtain the underwater refraction color corresponding to the fragment; The module finally outputs the underwater refraction color corresponding to the fragment. 6. the water surface simulation method in the real-time rendering according to claim 2, is characterized in that: The data required by the described reflection color generating module to the water surface are: the corresponding normal direction of the fragment, the reflection image of the water surface plane, and the corresponding position of the fragment in the screen space of the main camera in the world space; Next, for the operation steps: 1) Use the position corresponding to the fragment in the screen space of the main camera plus the normal direction corresponding to the fragment in the world space to obtain a two-dimensional vector; 2) Sampling the reflection image of the water surface plane with the two-dimensional vector to obtain the reflection color corresponding to the fragment; In general, the fragment finally outputs the water reflection color corresponding to the fragment.

Images