基于OpenGL的Loop网格细分

#include <math.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <assert.h> #include "loop.h" #define ALPHA_MAX 20 #define ALPHA_LIMIT 0.469 /* converges to ~ 0.469 */ GLfloat ALPHA[] = {1.13333, -0.358974, -0.333333, 0.129032, 0.945783, 2.0, 3.19889, 4.47885, 5.79946, 7.13634, 8.47535, 9.80865, 11.1322, 12.4441, 13.7439, 15.0317, 16.3082, 17.574, 18.83, 20.0769}; #define BETA_MAX 20 #define BETA_LIMIT 0.469 /* converges to ~ 0.469 */ GLfloat BETA[] = {0.46875, 1.21875, 1.125, 0.96875, 0.840932, 0.75, 0.686349, 0.641085, 0.60813, 0.583555, 0.564816, 0.55024, 0.5387, 0.529419, 0.52185, 0.515601, 0.510385, 0.505987, 0.502247, 0.49904 }; #define NEWVERTEX 123.0 GLfloat alpha(GLuint n); GLfloat beta(GLuint n); long writeOBJ(WingedEdge* we, char* filename) { FILE* file; Face* face; Vertex* vertex; GLfloat counter; long lines = 0; file = fopen(filename, "w"); if (!file) { fprintf(stderr, "writeOBJ() failed: can't open data file \"%s\".\n", filename); // Modified by owada return 0; } counter = 1.0; vertex = we->vertices; while (vertex) { fprintf(file, "v %f %f %f\n", vertex->x, vertex->y, vertex->z); lines++; vertex->averaged = new Vertex ; vertex->averaged->x = counter; counter += 1.0; vertex = vertex->next; } face = we->faces; while (face) { fprintf(file, "f %d %d %d\n", (int)(face->edge->head->averaged->x), (int)(face->edge->prev->head->averaged->x), (int)(face->edge->prev->prev->head->averaged->x)); lines++; face = face->next; } fclose(file); return lines; } WingedEdge* readOBJ(char* filename) { FILE* file; Model* model; WingedEdge* we; /* open the file */ file = fopen(filename, "r"); if (!file) { fprintf(stderr, "readOBJ() failed: can't open data file \"%s\".\n", filename); exit(1); } /* allocate a new model */ model = new Model ; model->position = new Vertex ; model->position->x = 0.0; model->position->y = 0.0; model->position->z = 0.0; firstPass(model, file); rewind(file); we = secondPass(model, file); return we; } GLvoid firstPass(Model* model, FILE* file) { GLuint numVertices; GLuint numFaces; char buf[128]; numVertices = numFaces = 0; while (fscanf(file, "%s", buf) != EOF) { switch (buf[0]) { case '#': /* comments*/ /* eat up the rest of the line */ fgets(buf, sizeof(buf), file); break; case 'v': /* a vertex! */ /* ignore all but the simple case */ numVertices++; fgets(buf, sizeof(buf), file); break; case 'f': /* a face! */ numFaces++; fgets(buf, sizeof(buf), file); break; default: /* I don't care about the other cases! */ fgets(buf, sizeof(buf), file); break; } } model->numFaces = numFaces; model->numVertices = numVertices; /* Our work here is done. */ } WingedEdge* secondPass(Model* model, FILE* file) { GLuint numVertices; GLuint numTriangles; GLuint v, f; GLuint v1, v2, v3; GLfloat x, y, z; Vertex** vertices = new Vertex*[model->numVertices]; /* array of vertices */ Triangle** triangles = new Triangle*[model->numFaces]; /* array of triangles */ Edge** edges = new Edge*[3 * model->numFaces]; /* array of edges */ /* List of faces! */ WingedEdge* we; Face* previous; Face* current; Vertex* currv; Vertex* prevv; char buf[128]; int i, j; numVertices = numTriangles= 0; while (fscanf(file, "%s", buf) != EOF) { switch (buf[0]) { case '#': /* comments */ fgets(buf, sizeof(buf), file); break; case 'v': /* vertex! */ fscanf(file, "%f %f %f", &x, &y, &z); vertices[numVertices] = new Vertex ; vertices[numVertices]->x = x; vertices[numVertices]->y = y; vertices[numVertices]->z = z; numVertices++; break; case 'f': fscanf(file, "%d %d %d", &v1, &v2, &v3); triangles[numTriangles] = new Triangle ; triangles[numTriangles]->verts[0] = v1 -1; /* THE -1 IS DAMN IMPORTANT! */ triangles[numTriangles]->verts[1] = v2 -1; triangles[numTriangles]->verts[2] = v3 -1; numTriangles++; break; default: /* I don't care about the rest */ fgets(buf, sizeof(buf), file); break; } } we = new WingedEdge ; we->faces = new Face ; /* allocate the first node */ previous = current = we->faces; /* all roads lead to initial node */ for (i=0; i < numTriangles; i++) { previous->next = current; /* link the last node in the list to the current node */ for (j=0; j<3; j++) { /* Create the half edges and inform them of the vertices and face. */ edges[3*i+j] = new Edge ; edges[3*i+j]->head = vertices[triangles[i]->verts[j%3]]; edges[3*i+j]->tail = vertices[triangles[i]->verts[(j+1)%3]]; edges[3*i+j]->left = current; } current->edge = edges[3*i]; /* associate an edge with the face */ for (j=0; j<3; j++) { edges[3*i+j]->prev = edges[3*i+(j+1)%3]; edges[3*i+j]->next = edges[3*i+(j+2)%3]; } /* onward to the next face */ previous = current; if (i+1 < numTriangles) current = new Face ; } for (i = 0; i < 3 * numTriangles -1; i++) { if (edges[i]->twin == NULL) { for (j = i+1; j < 3 * numTriangles; j++) { if (edges[j]->twin == NULL) { if (edges[j]->head == edges[i]->tail && edges[i]->head == edges[j]->tail) { edges[i]->twin = edges[j]; edges[j]->twin = edges[i]; } } } } } prevv = we->vertices = vertices[0]; /* start at the beginning */ for (i = 1; i < numVertices; i++) { currv = vertices[i]; prevv->next = currv; prevv = currv; } return we; } /* unitize: "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. * * we - pointer to the winged edge data classure */ GLfloat unitize(WingedEdge* we) { GLfloat maxx, minx, maxy, miny, maxz, minz; GLfloat cx, cy, cz, w, h, d; GLfloat scale; Vertex* vertex; assert(we); assert(we->vertices); /* and we'll just hope that the rest is ok */ vertex = we->vertices; /* get the max/mins */ maxx = minx = vertex->x; maxy = miny = vertex->y; maxz = minz = vertex->z; while (vertex) { if (maxx < vertex->x) maxx = vertex->x; if (minx > vertex->x) minx = vertex->x; if (maxy < vertex->y) maxy = vertex->y; if (miny > vertex->y) miny = vertex->y; if (maxz < vertex->z) maxz = vertex->z; if (minz > vertex->z) minz = vertex->z; vertex = vertex->next; } /* calculate model width, height, and depth */ w = sabs(maxx) + sabs(minx); h = sabs(maxy) + sabs(miny); d = sabs(maxz) + sabs(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 / sqrt(w*w+h*h+d*d); /* translate around center then scale */ vertex = we->vertices; while (vertex) { vertex->x -= cx; vertex->y -= cy; vertex->z -= cz; vertex->x *= scale; vertex->y *= scale; vertex->z *= scale; vertex = vertex->next; } return scale; } /* 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. * * we - pointer to winged edge data classure */ GLvoid facetNormals(WingedEdge* we) { Face* face; Edge* edge; Vertex* edge1; Vertex* edge2; assert(we); assert(we->faces); assert(we->faces->edge); /* and the rest we'll just pretend are ok */ face = we->faces; while (face) { edge1 = new Vertex ; edge2 = new Vertex ; edge1->x = face->edge->tail->x - face->edge->head->x; edge1->y = face->edge->tail->y - face->edge->head->y;