libgoatvr

annotate src/mesh.c @ 8:3d9ec6fe97d7

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- added distortion mesh generation for the OpenHMD module (unfinished) - changed internal implementation function naming to use the vrimp_ prefix - added an opengl helper function to load extension entry points
author John Tsiombikas <nuclear@member.fsf.org>
date Sat, 20 Sep 2014 13:22:53 +0300
parents
children d12592558809
rev   line source
nuclear@8 1 #include <stdio.h>
nuclear@8 2 #include <stdlib.h>
nuclear@8 3 #include <string.h>
nuclear@8 4 #include "opengl.h"
nuclear@8 5 #include "mesh.h"
nuclear@8 6
nuclear@8 7 static void distort_texcoords(float *tc, float aspect, float lens_center_offset, float scale,
nuclear@8 8 const float *dist_factors);
nuclear@8 9 static float barrel_scale(float rad, const float *k);
nuclear@8 10
nuclear@8 11 /* let's avoid a glew dependency in the library just for this */
nuclear@8 12 #ifndef GL_ARRAY_BUFFER
nuclear@8 13 #define GL_ARRAY_BUFFER 0x8892
nuclear@8 14 #define GL_ELEMENT_ARRAY_BUFFER 0x8893
nuclear@8 15 #define GL_STATIC_DRAW 0x88E4
nuclear@8 16 #endif
nuclear@8 17
nuclear@8 18 #if !defined(GL_VERSION_1_5) || !defined(GL_GLEXT_PROTOTYPES)
nuclear@8 19 static void (*glGenBuffers)(GLsizei, GLuint*);
nuclear@8 20 static void (*glDeleteBuffers)(GLsizei, GLuint*);
nuclear@8 21 static void (*glBufferData)(GLenum, unsigned int, const GLvoid*, GLenum);
nuclear@8 22 static void (*glBindBuffer)(GLenum, GLuint);
nuclear@8 23 #endif
nuclear@8 24
nuclear@8 25 int vrimp_mesh_init(struct mesh *m)
nuclear@8 26 {
nuclear@8 27 m->prim = GL_TRIANGLES;
nuclear@8 28
nuclear@8 29 m->varr = 0;
nuclear@8 30 m->iarr = 0;
nuclear@8 31 m->num_verts = m->num_faces = 0;
nuclear@8 32 m->vbo = m->ibo = 0;
nuclear@8 33
nuclear@8 34 if(!glGenBuffers) {
nuclear@8 35 glGenBuffers = vrimp_glfunc("glGenBuffersARB");
nuclear@8 36 glDeleteBuffers = vrimp_glfunc("glDeleteBuffersARB");
nuclear@8 37 glBufferData = vrimp_glfunc("glBufferDataARB");
nuclear@8 38 glBindBuffer = vrimp_glfunc("glBindBufferARB");
nuclear@8 39
nuclear@8 40 if(!(glGenBuffers && glDeleteBuffers && glBufferData && glBindBuffer)) {
nuclear@8 41 fprintf(stderr, "Failed to load VBO functions\n");
nuclear@8 42 return -1;
nuclear@8 43 }
nuclear@8 44 }
nuclear@8 45
nuclear@8 46 return 0;
nuclear@8 47 }
nuclear@8 48
nuclear@8 49 void vrimp_mesh_destroy(struct mesh *m)
nuclear@8 50 {
nuclear@8 51 free(m->varr);
nuclear@8 52 free(m->iarr);
nuclear@8 53
nuclear@8 54 if(m->vbo) glDeleteBuffers(1, &m->vbo);
nuclear@8 55 if(m->ibo) glDeleteBuffers(1, &m->ibo);
nuclear@8 56 }
nuclear@8 57
nuclear@8 58 void vrimp_mesh_draw(struct mesh *m)
nuclear@8 59 {
nuclear@8 60 glEnableClientState(GL_VERTEX_ARRAY);
nuclear@8 61 glEnableClientState(GL_TEXTURE_COORD_ARRAY);
nuclear@8 62
nuclear@8 63 glBindBuffer(GL_ARRAY_BUFFER, m->vbo);
nuclear@8 64 glVertexPointer(3, GL_FLOAT, sizeof(struct vertex), 0);
nuclear@8 65 glTexCoordPointer(2, GL_FLOAT, sizeof(struct vertex), (void*)offsetof(struct vertex, tx));
nuclear@8 66
nuclear@8 67 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m->ibo);
nuclear@8 68 glDrawElements(GL_TRIANGLES, m->num_faces * 3, GL_UNSIGNED_INT, 0);
nuclear@8 69
nuclear@8 70 glBindBuffer(GL_ARRAY_BUFFER, 0);
nuclear@8 71 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
nuclear@8 72
nuclear@8 73 glDisableClientState(GL_VERTEX_ARRAY);
nuclear@8 74 glDisableClientState(GL_TEXTURE_COORD_ARRAY);
nuclear@8 75 }
nuclear@8 76
nuclear@8 77 int vrimp_mesh_barrel_distortion(struct mesh *m, int usub, int vsub, float aspect,
nuclear@8 78 float lens_center_offset, float scale, const float *dist_factors,
nuclear@8 79 float tex_scale_x, float tex_scale_y)
nuclear@8 80 {
nuclear@8 81 int i, j;
nuclear@8 82 int uverts, vverts;
nuclear@8 83 int num_verts, num_quads, num_tris;
nuclear@8 84 struct vertex *varr, *vptr;
nuclear@8 85 unsigned int *iarr, *iptr;
nuclear@8 86 float du, dv;
nuclear@8 87
nuclear@8 88 uverts = usub + 1;
nuclear@8 89 vverts = vsub + 1;
nuclear@8 90
nuclear@8 91 num_verts = uverts * vverts;
nuclear@8 92 num_quads = usub * vsub;
nuclear@8 93 num_tris = num_quads * 2;
nuclear@8 94
nuclear@8 95 if(!(varr = malloc(num_verts * sizeof *varr))) {
nuclear@8 96 return -1;
nuclear@8 97 }
nuclear@8 98 if(!(iarr = malloc(num_tris * 3 * sizeof *iarr))) {
nuclear@8 99 free(varr);
nuclear@8 100 return -1;
nuclear@8 101 }
nuclear@8 102
nuclear@8 103 du = 1.0 / (float)usub;
nuclear@8 104 dv = 1.0 / (float)vsub;
nuclear@8 105
nuclear@8 106 vptr = varr;
nuclear@8 107 for(i=0; i<vverts; i++) {
nuclear@8 108 float v = (float)i * dv;
nuclear@8 109 float y = 2.0 * v - 1.0;
nuclear@8 110
nuclear@8 111 for(j=0; j<uverts; j++) {
nuclear@8 112 float u = (float)j * du;
nuclear@8 113 float x = 2.0 * u - 1.0;
nuclear@8 114 float tc[2];
nuclear@8 115 tc[0] = u;
nuclear@8 116 tc[1] = v;
nuclear@8 117
nuclear@8 118 distort_texcoords(tc, aspect, lens_center_offset, scale, dist_factors);
nuclear@8 119
nuclear@8 120 vptr->x = x;
nuclear@8 121 vptr->y = y;
nuclear@8 122 vptr->z = 0;
nuclear@8 123 vptr->tx = tc[0] * tex_scale_x;
nuclear@8 124 vptr->ty = tc[1] * tex_scale_y;
nuclear@8 125 vptr++;
nuclear@8 126 }
nuclear@8 127 }
nuclear@8 128
nuclear@8 129 iptr = iarr;
nuclear@8 130 for(i=0; i<vsub; i++) {
nuclear@8 131 for(j=0; j<usub; j++) {
nuclear@8 132 *iptr++ = i * uverts + j;
nuclear@8 133 *iptr++ = (i + 1) * uverts + j;
nuclear@8 134 *iptr++ = (i + 1) * uverts + (j + 1);
nuclear@8 135
nuclear@8 136 *iptr++ = i * uverts + j;
nuclear@8 137 *iptr++ = (i + 1) * uverts + (j + 1);
nuclear@8 138 *iptr++ = i * uverts + (j + 1);
nuclear@8 139 }
nuclear@8 140 }
nuclear@8 141
nuclear@8 142 glGenBuffers(1, &m->vbo);
nuclear@8 143 glGenBuffers(1, &m->ibo);
nuclear@8 144 glBindBuffer(GL_ARRAY_BUFFER, m->vbo);
nuclear@8 145 glBufferData(GL_ARRAY_BUFFER, num_verts * sizeof *varr, varr, GL_STATIC_DRAW);
nuclear@8 146 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m->ibo);
nuclear@8 147 glBufferData(GL_ELEMENT_ARRAY_BUFFER, num_tris * 3 * sizeof *iarr, iarr, GL_STATIC_DRAW);
nuclear@8 148
nuclear@8 149 m->prim = GL_TRIANGLES;
nuclear@8 150 m->num_verts = num_verts;
nuclear@8 151 m->num_faces = num_tris;
nuclear@8 152 return 0;
nuclear@8 153 }
nuclear@8 154
nuclear@8 155 static void distort_texcoords(float *tc, float aspect, float lens_center_offset, float scale,
nuclear@8 156 const float *dist_factors)
nuclear@8 157 {
nuclear@8 158 /* map tc [0, 1] -> [-1, 1] */
nuclear@8 159 float ptx = tc[0] * 2.0 - 1.0;
nuclear@8 160 float pty = tc[1] * 2.0 - 1.0;
nuclear@8 161 float rad;
nuclear@8 162
nuclear@8 163 ptx += lens_center_offset * 2.0;
nuclear@8 164 pty /= aspect; /* correct for aspect ratio */
nuclear@8 165
nuclear@8 166 rad = barrel_scale(ptx * ptx + pty * pty, dist_factors);
nuclear@8 167 ptx *= rad; /* scale the point by the computer distortion radius */
nuclear@8 168 pty *= rad;
nuclear@8 169
nuclear@8 170 ptx /= scale;
nuclear@8 171 pty /= scale;
nuclear@8 172
nuclear@8 173 pty *= aspect;
nuclear@8 174 ptx -= lens_center_offset * 2.0;
nuclear@8 175
nuclear@8 176 /* map back to range [0, 1] */
nuclear@8 177 tc[0] = ptx * 0.5 + 0.5;
nuclear@8 178 tc[1] = pty * 0.5 + 0.5;
nuclear@8 179 }
nuclear@8 180
nuclear@8 181 static float barrel_scale(float rad, const float *k)
nuclear@8 182 {
nuclear@8 183 float radsq = rad * rad;
nuclear@8 184 float radquad = radsq * radsq;
nuclear@8 185 return k[0] + k[1] * radsq + k[2] * radquad + k[3] * radquad * radsq;
nuclear@8 186 }