glm.c

嵌入式GUI OpenGL源代码。OpenGL是嵌入式开发中常用的一种GUI系统。

	/* eat up rest of line */
	fgets(buf, sizeof(buf), file);
	numvertices++;
	break;
      case 'n':				/* normal */
	/* eat up rest of line */
	fgets(buf, sizeof(buf), file);
	numnormals++;
	break;
      case 't':				/* texcoord */
	/* eat up rest of line */
	fgets(buf, sizeof(buf), file);
	numtexcoords++;
	break;
      default:
	printf("glmFirstPass(): Unknown token \"%s\".\n", buf);
	exit(1);
	break;
      }
      break;
    case 'm':
      fgets(buf, sizeof(buf), file);
      sscanf(buf, "%s %s", buf, buf);
      model->mtllibname = strdup(buf);
      glmReadMTL(model, buf);
      break;
    case 'u':
      /* eat up rest of line */
      fgets(buf, sizeof(buf), file);
      break;
    case 'g':				/* group */
      /* eat up rest of line */
      fgets(buf, sizeof(buf), file);
#if SINGLE_STRING_GROUP_NAMES
      sscanf(buf, "%s", buf);
#else
      buf[strlen(buf)-1] = '\0';	/* nuke '\n' */
#endif
      group = glmAddGroup(model, buf);
      break;
    case 'f':				/* face */
      v = n = t = 0;
      fscanf(file, "%s", buf);
      /* can be one of %d, %d//%d, %d/%d, %d/%d/%d %d//%d */
      if (strstr(buf, "//")) {
	/* v//n */
	sscanf(buf, "%d//%d", &v, &n);
	fscanf(file, "%d//%d", &v, &n);
	fscanf(file, "%d//%d", &v, &n);
	numtriangles++;
	group->numtriangles++;
	while(fscanf(file, "%d//%d", &v, &n) > 0) {
	  numtriangles++;
	  group->numtriangles++;
	}
      } else if (sscanf(buf, "%d/%d/%d", &v, &t, &n) == 3) {
	/* v/t/n */
	fscanf(file, "%d/%d/%d", &v, &t, &n);
	fscanf(file, "%d/%d/%d", &v, &t, &n);
	numtriangles++;
	group->numtriangles++;
	while(fscanf(file, "%d/%d/%d", &v, &t, &n) > 0) {
	  numtriangles++;
	  group->numtriangles++;
	}
      } else if (sscanf(buf, "%d/%d", &v, &t) == 2) {
	/* v/t */
	fscanf(file, "%d/%d", &v, &t);
	fscanf(file, "%d/%d", &v, &t);
	numtriangles++;
	group->numtriangles++;
	while(fscanf(file, "%d/%d", &v, &t) > 0) {
	  numtriangles++;
	  group->numtriangles++;
	}
      } else {
	/* v */
	fscanf(file, "%d", &v);
	fscanf(file, "%d", &v);
	numtriangles++;
	group->numtriangles++;
	while(fscanf(file, "%d", &v) > 0) {
	  numtriangles++;
	  group->numtriangles++;
	}
      }
      break;

    default:
      /* eat up rest of line */
      fgets(buf, sizeof(buf), file);
      break;
    }
  }

  /* set the stats in the model structure */
  model->numvertices  = numvertices;
  model->numnormals   = numnormals;
  model->numtexcoords = numtexcoords;
  model->numtriangles = numtriangles;

  /* allocate memory for the triangles in each group */
  group = model->groups;
  while(group) {
    group->triangles = (GLuint*)malloc(sizeof(GLuint) * group->numtriangles);
    group->numtriangles = 0;
    group = group->next;
  }
}

/* glmSecondPass: second pass at a Wavefront OBJ file that gets all
 * the data.
 *
 * model - properly initialized GLMmodel structure
 * file  - (fopen'd) file descriptor 
 */
static GLvoid
glmSecondPass(GLMmodel* model, FILE* file) 
{
  GLuint    numvertices;		/* number of vertices in model */
  GLuint    numnormals;			/* number of normals in model */
  GLuint    numtexcoords;		/* number of texcoords in model */
  GLuint    numtriangles;		/* number of triangles in model */
  GLfloat*  vertices;			/* array of vertices  */
  GLfloat*  normals;			/* array of normals */
  GLfloat*  texcoords;			/* array of texture coordinates */
  GLMgroup* group;			/* current group pointer */
  GLuint    material;			/* current material */
  GLuint    v, n, t;
  char      buf[128];

  /* set the pointer shortcuts */
  vertices     = model->vertices;
  normals      = model->normals;
  texcoords    = model->texcoords;
  group        = model->groups;

  /* on the second pass through the file, read all the data into the
     allocated arrays */
  numvertices = numnormals = numtexcoords = 1;
  numtriangles = 0;
  material = 0;
  while(fscanf(file, "%s", buf) != EOF) {
    switch(buf[0]) {
    case '#':				/* comment */
      /* eat up rest of line */
      fgets(buf, sizeof(buf), file);
      break;
    case 'v':				/* v, vn, vt */
      switch(buf[1]) {
      case '\0':			/* vertex */
	fscanf(file, "%f %f %f", 
	       &vertices[3 * numvertices + 0], 
	       &vertices[3 * numvertices + 1], 
	       &vertices[3 * numvertices + 2]);
	numvertices++;
	break;
      case 'n':				/* normal */
	fscanf(file, "%f %f %f", 
	       &normals[3 * numnormals + 0],
	       &normals[3 * numnormals + 1], 
	       &normals[3 * numnormals + 2]);
	numnormals++;
	break;
      case 't':				/* texcoord */
	fscanf(file, "%f %f", 
	       &texcoords[2 * numtexcoords + 0],
	       &texcoords[2 * numtexcoords + 1]);
	numtexcoords++;
	break;
      }
      break;
    case 'u':
      fgets(buf, sizeof(buf), file);
      sscanf(buf, "%s %s", buf, buf);
      group->material = material = glmFindMaterial(model, buf);
      break;
    case 'g':				/* group */
      /* eat up rest of line */
      fgets(buf, sizeof(buf), file);
#if SINGLE_STRING_GROUP_NAMES
      sscanf(buf, "%s", buf);
#else
      buf[strlen(buf)-1] = '\0';	/* nuke '\n' */
#endif
      group = glmFindGroup(model, buf);
      group->material = material;
      break;
    case 'f':				/* face */
      v = n = t = 0;
      fscanf(file, "%s", buf);
      /* can be one of %d, %d//%d, %d/%d, %d/%d/%d %d//%d */
      if (strstr(buf, "//")) {
	/* v//n */
	sscanf(buf, "%d//%d", &v, &n);
	T(numtriangles).vindices[0] = v;
	T(numtriangles).nindices[0] = n;
	fscanf(file, "%d//%d", &v, &n);
	T(numtriangles).vindices[1] = v;
	T(numtriangles).nindices[1] = n;
	fscanf(file, "%d//%d", &v, &n);
	T(numtriangles).vindices[2] = v;
	T(numtriangles).nindices[2] = n;
	group->triangles[group->numtriangles++] = numtriangles;
	numtriangles++;
	while(fscanf(file, "%d//%d", &v, &n) > 0) {
	  T(numtriangles).vindices[0] = T(numtriangles-1).vindices[0];
	  T(numtriangles).nindices[0] = T(numtriangles-1).nindices[0];
	  T(numtriangles).vindices[1] = T(numtriangles-1).vindices[2];
	  T(numtriangles).nindices[1] = T(numtriangles-1).nindices[2];
	  T(numtriangles).vindices[2] = v;
	  T(numtriangles).nindices[2] = n;
	  group->triangles[group->numtriangles++] = numtriangles;
	  numtriangles++;
	}
      } else if (sscanf(buf, "%d/%d/%d", &v, &t, &n) == 3) {
	/* v/t/n */
	T(numtriangles).vindices[0] = v;
	T(numtriangles).tindices[0] = t;
	T(numtriangles).nindices[0] = n;
	fscanf(file, "%d/%d/%d", &v, &t, &n);
	T(numtriangles).vindices[1] = v;
	T(numtriangles).tindices[1] = t;
	T(numtriangles).nindices[1] = n;
	fscanf(file, "%d/%d/%d", &v, &t, &n);
	T(numtriangles).vindices[2] = v;
	T(numtriangles).tindices[2] = t;
	T(numtriangles).nindices[2] = n;
	group->triangles[group->numtriangles++] = numtriangles;
	numtriangles++;
	while(fscanf(file, "%d/%d/%d", &v, &t, &n) > 0) {
	  T(numtriangles).vindices[0] = T(numtriangles-1).vindices[0];
	  T(numtriangles).tindices[0] = T(numtriangles-1).tindices[0];
	  T(numtriangles).nindices[0] = T(numtriangles-1).nindices[0];
	  T(numtriangles).vindices[1] = T(numtriangles-1).vindices[2];
	  T(numtriangles).tindices[1] = T(numtriangles-1).tindices[2];
	  T(numtriangles).nindices[1] = T(numtriangles-1).nindices[2];
	  T(numtriangles).vindices[2] = v;
	  T(numtriangles).tindices[2] = t;
	  T(numtriangles).nindices[2] = n;
	  group->triangles[group->numtriangles++] = numtriangles;
	  numtriangles++;
	}
      } else if (sscanf(buf, "%d/%d", &v, &t) == 2) {
	/* v/t */
	T(numtriangles).vindices[0] = v;
	T(numtriangles).tindices[0] = t;
	fscanf(file, "%d/%d", &v, &t);
	T(numtriangles).vindices[1] = v;
	T(numtriangles).tindices[1] = t;
	fscanf(file, "%d/%d", &v, &t);
	T(numtriangles).vindices[2] = v;
	T(numtriangles).tindices[2] = t;
	group->triangles[group->numtriangles++] = numtriangles;
	numtriangles++;
	while(fscanf(file, "%d/%d", &v, &t) > 0) {
	  T(numtriangles).vindices[0] = T(numtriangles-1).vindices[0];
	  T(numtriangles).tindices[0] = T(numtriangles-1).tindices[0];
	  T(numtriangles).vindices[1] = T(numtriangles-1).vindices[2];
	  T(numtriangles).tindices[1] = T(numtriangles-1).tindices[2];
	  T(numtriangles).vindices[2] = v;
	  T(numtriangles).tindices[2] = t;
	  group->triangles[group->numtriangles++] = numtriangles;
	  numtriangles++;
	}
      } else {
	/* v */
	sscanf(buf, "%d", &v);
	T(numtriangles).vindices[0] = v;
	fscanf(file, "%d", &v);
	T(numtriangles).vindices[1] = v;
	fscanf(file, "%d", &v);
	T(numtriangles).vindices[2] = v;
	group->triangles[group->numtriangles++] = numtriangles;
	numtriangles++;
	while(fscanf(file, "%d", &v) > 0) {
	  T(numtriangles).vindices[0] = T(numtriangles-1).vindices[0];
	  T(numtriangles).vindices[1] = T(numtriangles-1).vindices[2];
	  T(numtriangles).vindices[2] = v;
	  group->triangles[group->numtriangles++] = numtriangles;
	  numtriangles++;
	}
      }
      break;

    default:
      /* eat up rest of line */
      fgets(buf, sizeof(buf), file);
      break;
    }
  }

#if 0
  /* announce the memory requirements */
  printf(" Memory: %d bytes\n",
	 numvertices  * 3*sizeof(GLfloat) +
	 numnormals   * 3*sizeof(GLfloat) * (numnormals ? 1 : 0) +
	 numtexcoords * 3*sizeof(GLfloat) * (numtexcoords ? 1 : 0) +
	 numtriangles * sizeof(GLMtriangle));
#endif
}




/* glmUnitize: "unitize" a model by translating it to the origin and
 * scaling it to fit in a unit cube around the origin (-1 to 1 in all
 * dimensions).  
 * Returns the scalefactor used.
 *
 * model - properly initialized GLMmodel structure 
 */
GLfloat
glmUnitize(GLMmodel* model)
{
  GLuint  i;
  GLfloat maxx, minx, maxy, miny, maxz, minz;
  GLfloat cx, cy, cz, w, h, d;
  GLfloat scale;

  assert(model);
  assert(model->vertices);

  /* get the max/mins */
  maxx = minx = model->vertices[3 + 0];
  maxy = miny = model->vertices[3 + 1];
  maxz = minz = model->vertices[3 + 2];
  for (i = 1; i <= model->numvertices; i++) {
    if (maxx < model->vertices[3 * i + 0])
      maxx = model->vertices[3 * i + 0];
    if (minx > model->vertices[3 * i + 0])
      minx = model->vertices[3 * i + 0];

    if (maxy < model->vertices[3 * i + 1])
      maxy = model->vertices[3 * i + 1];
    if (miny > model->vertices[3 * i + 1])
      miny = model->vertices[3 * i + 1];

    if (maxz < model->vertices[3 * i + 2])
      maxz = model->vertices[3 * i + 2];
    if (minz > model->vertices[3 * i + 2])
      minz = model->vertices[3 * i + 2];
  }

  /* calculate model width, height, and depth */
  w = glmAbs(maxx) + glmAbs(minx);
  h = glmAbs(maxy) + glmAbs(miny);
  d = glmAbs(maxz) + glmAbs(minz);

  /* calculate center of the model */
  cx = (maxx + minx) / 2.0;
  cy = (maxy + miny) / 2.0;
  cz = (maxz + minz) / 2.0;

  /* calculate unitizing scale factor */
  scale = 2.0 / glmMax(glmMax(w, h), d);

  /* translate around center then scale */
  for (i = 1; i <= model->numvertices; i++) {
    model->vertices[3 * i + 0] -= cx;
    model->vertices[3 * i + 1] -= cy;
    model->vertices[3 * i + 2] -= cz;
    model->vertices[3 * i + 0] *= scale;
    model->vertices[3 * i + 1] *= scale;
    model->vertices[3 * i + 2] *= scale;
  }

  return scale;
}

/* 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)
{
  GLuint i;
  GLfloat maxx, minx, maxy, miny, maxz, minz;

  assert(model);
  assert(model->vertices);
  assert(dimensions);

  /* get the max/mins */
  maxx = minx = model->vertices[3 + 0];
  maxy = miny = model->vertices[3 + 1];
  maxz = minz = model->vertices[3 + 2];
  for (i = 1; i <= model->numvertices; i++) {
    if (maxx < model->vertices[3 * i + 0])
      maxx = model->vertices[3 * i + 0];
    if (minx > model->vertices[3 * i + 0])
      minx = model->vertices[3 * i + 0];

    if (maxy < model->vertices[3 * i + 1])
      maxy = model->vertices[3 * i + 1];
    if (miny > model->vertices[3 * i + 1])
      miny = model->vertices[3 * i + 1];

    if (maxz < model->vertices[3 * i + 2])
      maxz = model->vertices[3 * i + 2];
    if (minz > model->vertices[3 * i + 2])
      minz = model->vertices[3 * i + 2];
  }

  /* calculate model width, height, and depth */
  dimensions[0] = glmAbs(maxx) + glmAbs(minx);
  dimensions[1] = glmAbs(maxy) + glmAbs(miny);
  dimensions[2] = glmAbs(maxz) + glmAbs(minz);
}

/* 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)
{
  GLuint i;

  for (i = 1; i <= model->numvertices; i++) {
    model->vertices[3 * i + 0] *= scale;
    model->vertices[3 * i + 1] *= scale;
    model->vertices[3 * i + 2] *= 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)
{
  GLuint i, swap;

  assert(model);

  for (i = 0; i < model->numtriangles; i++) {
    swap = T(i).vindices[0];
    T(i).vindices[0] = T(i).vindices[2];
    T(i).vindices[2] = swap;

    if (model->numnormals) {
      swap = T(i).nindices[0];
      T(i).nindices[0] = T(i).nindices[2];
      T(i).nindices[2] = swap;
    }

    if (model->numtexcoords) {
      swap = T(i).tindices[0];
      T(i).tindices[0] = T(i).tindices[2];
      T(i).tindices[2] = swap;
    }
  }