progs/tests/fbotexture.c

   1 /*
   2  * Test GL_EXT_framebuffer_object render-to-texture
   3  *
   4  * Draw a teapot into a texture image with stenciling.
   5  * Then draw a textured quad using that texture.
   6  *
   7  * Brian Paul
   8  * 18 Apr 2005
   9  */
  10
  11
  12 #define GL_GLEXT_PROTOTYPES
  13 #include <assert.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <math.h>
  17 #include <GL/glut.h>
  18
  19 static int Width = 400, Height = 400;
  20 static int TexWidth = 512, TexHeight = 512;
  21 static GLuint MyFB;
  22 static GLuint TexObj;
  23 static GLuint DepthRB, StencilRB;
  24 static GLboolean Anim = GL_FALSE;
  25 static GLfloat Rot = 0.0;
  26
  27
  28 static void
  29 CheckError(int line)
  30 {
  31    GLenum err = glGetError();
  32    if (err) {
  33       printf("GL Error 0x%x at line %d\n", (int) err, line);
  34    }
  35 }
  36
  37
  38 static void
  39 Idle(void)
  40 {
  41    Rot = glutGet(GLUT_ELAPSED_TIME) * 0.05;
  42    glutPostRedisplay();
  43 }
  44
  45
  46 static void
  47 RenderTexture(void)
  48 {
  49    GLint level = 0;
  50    GLenum status;
  51
  52    glMatrixMode(GL_PROJECTION);
  53    glLoadIdentity();
  54    glOrtho(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  55    glMatrixMode(GL_MODELVIEW);
  56    glLoadIdentity();
  57    glTranslatef(0.0, 0.0, -15.0);
  58
  59    /* draw to texture */
  60    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
  61    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
  62                              GL_TEXTURE_2D, TexObj, level);
  63
  64    status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
  65    if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
  66       printf("Framebuffer incomplete!!!\n");
  67    }
  68
  69    glViewport(0, 0, TexWidth, TexHeight);
  70
  71    glClearColor(0.5, 0.5, 1.0, 0.0);
  72    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
  73
  74    glEnable(GL_DEPTH_TEST);
  75    glEnable(GL_STENCIL_TEST);
  76    glStencilFunc(GL_NEVER, 1, ~0);
  77    glStencilOp(GL_REPLACE, GL_KEEP, GL_REPLACE);
  78
  79    /* draw diamond-shaped stencil pattern */
  80    glColor3f(0, 1, 0);
  81    glBegin(GL_POLYGON);
  82    glVertex2f(-0.2,  0.0);
  83    glVertex2f( 0.0, -0.2);
  84    glVertex2f( 0.2,  0.0);
  85    glVertex2f( 0.0,  0.2);
  86    glEnd();
  87
  88    /* draw teapot where stencil != 1 */
  89    glStencilFunc(GL_NOTEQUAL, 1, ~0);
  90    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
  91
  92 #if 0
  93    glBegin(GL_POLYGON);
  94    glColor3f(1, 0, 0);
  95    glVertex2f(-1, -1);
  96    glColor3f(0, 1, 0);
  97    glVertex2f(1, -1);
  98    glColor3f(0, 0, 1);
  99    glVertex2f(0, 1);
 100    glEnd();
 101 #else
 102    glEnable(GL_LIGHTING);
 103    glEnable(GL_LIGHT0);
 104    glPushMatrix();
 105    glRotatef(0.5 * Rot, 1.0, 0.0, 0.0);
 106    glutSolidTeapot(0.5);
 107    glPopMatrix();
 108    glDisable(GL_LIGHTING);
 109 #endif
 110    glDisable(GL_DEPTH_TEST);
 111    glDisable(GL_STENCIL_TEST);
 112
 113    /* Bind normal framebuffer */
 114    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 115
 116    CheckError(__LINE__);
 117 }
 118
 119
 120
 121 static void
 122 Display(void)
 123 {
 124    float ar = (float) Width / (float) Height;
 125
 126    RenderTexture();
 127
 128    /* draw textured quad in the window */
 129
 130    glMatrixMode(GL_PROJECTION);
 131    glLoadIdentity();
 132    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 25.0);
 133    glMatrixMode(GL_MODELVIEW);
 134    glLoadIdentity();
 135    glTranslatef(0.0, 0.0, -7.0);
 136
 137    glViewport(0, 0, Width, Height);
 138
 139    glClearColor(0.25, 0.25, 0.25, 0);
 140    glClear(GL_COLOR_BUFFER_BIT);
 141
 142    glPushMatrix();
 143    glRotatef(Rot, 0, 1, 0);
 144    glEnable(GL_TEXTURE_2D);
 145    glBegin(GL_POLYGON);
 146    glColor3f(0.25, 0.25, 0.25);
 147    glTexCoord2f(0, 0);
 148    glVertex2f(-1, -1);
 149    glTexCoord2f(1, 0);
 150    glVertex2f(1, -1);
 151    glColor3f(1.0, 1.0, 1.0);
 152    glTexCoord2f(1, 1);
 153    glVertex2f(1, 1);
 154    glTexCoord2f(0, 1);
 155    glVertex2f(-1, 1);
 156    glEnd();
 157    glPopMatrix();
 158    glDisable(GL_TEXTURE_2D);
 159
 160    glutSwapBuffers();
 161    CheckError(__LINE__);
 162 }
 163
 164
 165 static void
 166 Reshape(int width, int height)
 167 {
 168    glViewport(0, 0, width, height);
 169    Width = width;
 170    Height = height;
 171 }
 172
 173
 174 static void
 175 Key(unsigned char key, int x, int y)
 176 {
 177    (void) x;
 178    (void) y;
 179    switch (key) {
 180       case 'a':
 181          Anim = !Anim;
 182          if (Anim)
 183             glutIdleFunc(Idle);
 184          else
 185             glutIdleFunc(NULL);
 186          break;
 187       case 27:
 188          exit(0);
 189          break;
 190    }
 191    glutPostRedisplay();
 192 }
 193
 194
 195 static void
 196 Init(void)
 197 {
 198    GLint i;
 199
 200    if (!glutExtensionSupported("GL_EXT_framebuffer_object")) {
 201       printf("GL_EXT_framebuffer_object not found!\n");
 202       exit(0);
 203    }
 204    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 205
 206    /* make framebuffer */
 207    glGenFramebuffersEXT(1, &MyFB);
 208    assert(MyFB);
 209    assert(!glIsFramebufferEXT(MyFB));
 210    glDeleteFramebuffersEXT(1, &MyFB);
 211    assert(!glIsFramebufferEXT(MyFB));
 212    /* Note, continue to use MyFB below */
 213
 214    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
 215    assert(glIsFramebufferEXT(MyFB));
 216    glGetIntegerv(GL_FRAMEBUFFER_BINDING_EXT, &i);
 217    assert(i == MyFB);
 218
 219    /* make depth renderbuffer */
 220    glGenRenderbuffersEXT(1, &DepthRB);
 221    assert(DepthRB);
 222    assert(!glIsRenderbufferEXT(DepthRB));
 223    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, DepthRB);
 224    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT,
 225                             TexWidth, TexHeight);
 226    glGetRenderbufferParameterivEXT(GL_RENDERBUFFER_EXT,
 227                                    GL_RENDERBUFFER_DEPTH_SIZE_EXT, &i);
 228    printf("Depth renderbuffer size = %d bits\n", i);
 229    assert(i > 0);
 230
 231    /* make stencil renderbuffer */
 232    glGenRenderbuffersEXT(1, &StencilRB);
 233    assert(StencilRB);
 234    assert(!glIsRenderbufferEXT(StencilRB));
 235    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, StencilRB);
 236    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_STENCIL_INDEX,
 237                             TexWidth, TexHeight);
 238    glGetRenderbufferParameterivEXT(GL_RENDERBUFFER_EXT,
 239                                    GL_RENDERBUFFER_STENCIL_SIZE_EXT, &i);
 240    printf("Stencil renderbuffer size = %d bits\n", i);
 241    assert(i > 0);
 242
 243    /* attach DepthRB to MyFB */
 244    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
 245                                 GL_RENDERBUFFER_EXT, DepthRB);
 246
 247    /* attach StencilRB to MyFB */
 248    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
 249                                 GL_RENDERBUFFER_EXT, StencilRB);
 250
 251
 252    /* bind regular framebuffer */
 253    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 254
 255    /* Make texture object/image */
 256    glGenTextures(1, &TexObj);
 257    glBindTexture(GL_TEXTURE_2D, TexObj);
 258    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, TexWidth, TexHeight, 0,
 259                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 260    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 261    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 262    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 263
 264    CheckError(__LINE__);
 265 }
 266
 267
 268 int
 269 main(int argc, char *argv[])
 270 {
 271    glutInit(&argc, argv);
 272    glutInitWindowPosition(0, 0);
 273    glutInitWindowSize(Width, Height);
 274    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 275    glutCreateWindow(argv[0]);
 276    glutReshapeFunc(Reshape);
 277    glutKeyboardFunc(Key);
 278    glutDisplayFunc(Display);
 279    if (Anim)
 280       glutIdleFunc(Idle);
 281    Init();
 282    glutMainLoop();
 283    return 0;
 284 }