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glm.h
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/*
glm.h
Nate Robins, 1997, 2000
nate@pobox.com, http://www.pobox.com/~nate
Wavefront OBJ model file format reader/writer/manipulator.
Includes routines for generating smooth normals with
preservation of edges, welding redundant vertices & texture
coordinate generation (spheremap and planar projections) + more.
*/
#if defined(__APPLE__) || defined(MACOSX)
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
#ifndef M_PI
#define M_PI 3.14159265f
#endif
#define GLM_NONE (0) /* render with only vertices */
#define GLM_FLAT (1 << 0) /* render with facet normals */
#define GLM_SMOOTH (1 << 1) /* render with vertex normals */
#define GLM_TEXTURE (1 << 2) /* render with texture coords */
#define GLM_COLOR (1 << 3) /* render with colors */
#define GLM_MATERIAL (1 << 4) /* render with materials */
/* GLMmaterial: Structure that defines a material in a model.
*/
typedef struct _GLMmaterial
{
char* name; /* name of material */
GLfloat diffuse[4]; /* diffuse component */
GLfloat ambient[4]; /* ambient component */
GLfloat specular[4]; /* specular component */
GLfloat emmissive[4]; /* emmissive component */
GLfloat shininess; /* specular exponent */
} GLMmaterial;
/* GLMtriangle: Structure that defines a triangle in a model.
*/
typedef struct _GLMtriangle {
GLuint vindices[3]; /* array of triangle vertex indices */
GLuint nindices[3]; /* array of triangle normal indices */
GLuint tindices[3]; /* array of triangle texcoord indices*/
GLuint findex; /* index of triangle facet normal */
} GLMtriangle;
/* GLMgroup: Structure that defines a group in a model.
*/
typedef struct _GLMgroup {
char* name; /* name of this group */
GLuint numtriangles; /* number of triangles in this group */
GLuint* triangles; /* array of triangle indices */
GLuint material; /* index to material for group */
struct _GLMgroup* next; /* pointer to next group in model */
} GLMgroup;
/* GLMmodel: Structure that defines a model.
*/
typedef struct _GLMmodel {
char* pathname; /* path to this model */
char* mtllibname; /* name of the material library */
GLuint numvertices; /* number of vertices in model */
GLfloat* vertices; /* array of vertices */
GLuint numnormals; /* number of normals in model */
GLfloat* normals; /* array of normals */
GLuint numtexcoords; /* number of texcoords in model */
GLfloat* texcoords; /* array of texture coordinates */
GLuint numfacetnorms; /* number of facetnorms in model */
GLfloat* facetnorms; /* array of facetnorms */
GLuint numtriangles; /* number of triangles in model */
GLMtriangle* triangles; /* array of triangles */
GLuint nummaterials; /* number of materials in model */
GLMmaterial* materials; /* array of materials */
GLuint numgroups; /* number of groups in model */
GLMgroup* groups; /* linked list of groups */
GLfloat position[3]; /* position of the model */
} GLMmodel;
/* glmUnitize: "unitize" a model by translating it to the origin and
* scaling it to fit in a unit cube around the origin. Returns the
* scalefactor used.
*
* model - properly initialized GLMmodel structure
*/
GLfloat
glmUnitize(GLMmodel* model);
/* glmDimensions: Calculates the dimensions (width, height, depth) of
* a model.
*
* model - initialized GLMmodel structure
* dimensions - array of 3 GLfloats (GLfloat dimensions[3])
*/
GLvoid
glmDimensions(GLMmodel* model, GLfloat* dimensions);
/* glmScale: Scales a model by a given amount.
*
* model - properly initialized GLMmodel structure
* scale - scalefactor (0.5 = half as large, 2.0 = twice as large)
*/
GLvoid
glmScale(GLMmodel* model, GLfloat scale);
/* glmReverseWinding: Reverse the polygon winding for all polygons in
* this model. Default winding is counter-clockwise. Also changes
* the direction of the normals.
*
* model - properly initialized GLMmodel structure
*/
GLvoid
glmReverseWinding(GLMmodel* model);
/* glmFacetNormals: Generates facet normals for a model (by taking the
* cross product of the two vectors derived from the sides of each
* triangle). Assumes a counter-clockwise winding.
*
* model - initialized GLMmodel structure
*/
GLvoid
glmFacetNormals(GLMmodel* model);
/* glmVertexNormals: Generates smooth vertex normals for a model.
* First builds a list of all the triangles each vertex is in. Then
* loops through each vertex in the the list averaging all the facet
* normals of the triangles each vertex is in. Finally, sets the
* normal index in the triangle for the vertex to the generated smooth
* normal. If the dot product of a facet normal and the facet normal
* associated with the first triangle in the list of triangles the
* current vertex is in is greater than the cosine of the angle
* parameter to the function, that facet normal is not added into the
* average normal calculation and the corresponding vertex is given
* the facet normal. This tends to preserve hard edges. The angle to
* use depends on the model, but 90 degrees is usually a good start.
*
* model - initialized GLMmodel structure
* angle - maximum angle (in degrees) to smooth across
*/
GLvoid
glmVertexNormals(GLMmodel* model, GLfloat angle);
/* glmLinearTexture: Generates texture coordinates according to a
* linear projection of the texture map. It generates these by
* linearly mapping the vertices onto a square.
*
* model - pointer to initialized GLMmodel structure
*/
GLvoid
glmLinearTexture(GLMmodel* model);
/* glmSpheremapTexture: Generates texture coordinates according to a
* spherical projection of the texture map. Sometimes referred to as
* spheremap, or reflection map texture coordinates. It generates
* these by using the normal to calculate where that vertex would map
* onto a sphere. Since it is impossible to map something flat
* perfectly onto something spherical, there is distortion at the
* poles. This particular implementation causes the poles along the X
* axis to be distorted.
*
* model - pointer to initialized GLMmodel structure
*/
GLvoid
glmSpheremapTexture(GLMmodel* model);
/* glmDelete: Deletes a GLMmodel structure.
*
* model - initialized GLMmodel structure
*/
GLvoid
glmDelete(GLMmodel* model);
/* glmReadOBJ: Reads a model description from a Wavefront .OBJ file.
* Returns a pointer to the created object which should be free'd with
* glmDelete().
*
* filename - name of the file containing the Wavefront .OBJ format data.
*/
GLMmodel*
glmReadOBJ(char* filename);
/* glmWriteOBJ: Writes a model description in Wavefront .OBJ format to
* a file.
*
* model - initialized GLMmodel structure
* filename - name of the file to write the Wavefront .OBJ format data to
* mode - a bitwise or of values describing what is written to the file
* GLM_NONE - write only vertices
* GLM_FLAT - write facet normals
* GLM_SMOOTH - write vertex normals
* GLM_TEXTURE - write texture coords
* GLM_FLAT and GLM_SMOOTH should not both be specified.
*/
GLvoid
glmWriteOBJ(GLMmodel* model, char* filename, GLuint mode);
/* glmDraw: Renders the model to the current OpenGL context using the
* mode specified.
*
* model - initialized GLMmodel structure
* mode - a bitwise OR of values describing what is to be rendered.
* GLM_NONE - render with only vertices
* GLM_FLAT - render with facet normals
* GLM_SMOOTH - render with vertex normals
* GLM_TEXTURE - render with texture coords
* GLM_FLAT and GLM_SMOOTH should not both be specified.
*/
GLvoid
glmDraw(GLMmodel* model, GLuint mode);
/* glmList: Generates and returns a display list for the model using
* the mode specified.
*
* model - initialized GLMmodel structure
* mode - a bitwise OR of values describing what is to be rendered.
* GLM_NONE - render with only vertices
* GLM_FLAT - render with facet normals
* GLM_SMOOTH - render with vertex normals
* GLM_TEXTURE - render with texture coords
* GLM_FLAT and GLM_SMOOTH should not both be specified.
*/
GLuint
glmList(GLMmodel* model, GLuint mode);
/* glmWeld: eliminate (weld) vectors that are within an epsilon of
* each other.
*
* model - initialized GLMmodel structure
* epsilon - maximum difference between vertices
* ( 0.00001 is a good start for a unitized model)
*
*/
GLvoid
glmWeld(GLMmodel* model, GLfloat epsilon);
/* glmReadPPM: read a PPM raw (type P6) file. The PPM file has a header
* that should look something like:
*
* P6
* # comment
* width height max_value
* rgbrgbrgb...
*
* where "P6" is the magic cookie which identifies the file type and
* should be the only characters on the first line followed by a
* carriage return. Any line starting with a # mark will be treated
* as a comment and discarded. After the magic cookie, three integer
* values are expected: width, height of the image and the maximum
* value for a pixel (max_value must be < 256 for PPM raw files). The
* data section consists of width*height rgb triplets (one byte each)
* in binary format (i.e., such as that written with fwrite() or
* equivalent).
*
* The rgb data is returned as an array of unsigned chars (packed
* rgb). The malloc()'d memory should be free()'d by the caller. If
* an error occurs, an error message is sent to stderr and NULL is
* returned.
*
* filename - name of the .ppm file.
* width - will contain the width of the image on return.
* height - will contain the height of the image on return.
*
*/
GLubyte*
glmReadPPM(char* filename, int* width, int* height);