progs/trivial/tri-fbo-tex.c

   1 /* Framebuffer object test */
   2
   3
   4 #include <GL/glew.h>
   5 #include <GL/glut.h>
   6 #include <assert.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <math.h>
  11
  12 /* For debug */
  13
  14
  15 static int Win = 0;
  16 static int Width = 512, Height = 512;
  17
  18 static GLenum TexTarget = GL_TEXTURE_2D;
  19 static int TexWidth = 512, TexHeight = 512;
  20
  21 static GLuint MyFB;
  22 static GLuint TexObj;
  23 static GLboolean Anim = GL_FALSE;
  24 static GLfloat Rot = 0.0;
  25 static GLuint TextureLevel = 0;  /* which texture level to render to */
  26 static GLenum TexIntFormat = GL_RGB; /* either GL_RGB or GL_RGBA */
  27
  28
  29 static void
  30 CheckError(int line)
  31 {
  32    GLenum err = glGetError();
  33    if (err) {
  34       printf("GL Error 0x%x at line %d\n", (int) err, line);
  35    }
  36 }
  37
  38
  39 static void
  40 Idle(void)
  41 {
  42    Rot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
  43    glutPostRedisplay();
  44 }
  45
  46
  47 static void
  48 RenderTexture(void)
  49 {
  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    if (1) {
  60       /* draw to texture image */
  61       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
  62
  63       status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
  64       if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
  65          printf("Framebuffer incomplete!!!\n");
  66       }
  67
  68       glViewport(0, 0, TexWidth, TexHeight);
  69
  70       glClearColor(0.5, 0.5, 1.0, 0.0);
  71       glClear(GL_COLOR_BUFFER_BIT);
  72
  73       CheckError(__LINE__);
  74
  75       glBegin(GL_POLYGON);
  76       glColor3f(1, 0, 0);
  77       glVertex2f(-1, -1);
  78       glColor3f(0, 1, 0);
  79       glVertex2f(1, -1);
  80       glColor3f(0, 0, 1);
  81       glVertex2f(0, 1);
  82       glEnd();
  83
  84       /* Bind normal framebuffer */
  85       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
  86    }
  87    else {
  88    }
  89
  90    CheckError(__LINE__);
  91 }
  92
  93
  94
  95 static void
  96 Display(void)
  97 {
  98    float ar = (float) Width / (float) Height;
  99
 100    RenderTexture();
 101
 102    /* draw textured quad in the window */
 103    glMatrixMode(GL_PROJECTION);
 104    glLoadIdentity();
 105    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 25.0);
 106    glMatrixMode(GL_MODELVIEW);
 107    glLoadIdentity();
 108    glTranslatef(0.0, 0.0, -7.0);
 109
 110    glViewport(0, 0, Width, Height);
 111
 112    glClearColor(0.25, 0.25, 0.25, 0);
 113    glClear(GL_COLOR_BUFFER_BIT);
 114
 115    glPushMatrix();
 116    glRotatef(Rot, 0, 1, 0);
 117    glEnable(TexTarget);
 118    glBindTexture(TexTarget, TexObj);
 119
 120    {
 121       glBegin(GL_POLYGON);
 122       glColor3f(0.25, 0.25, 0.25);
 123       glTexCoord2f(0, 0);
 124       glVertex2f(-1, -1);
 125       glTexCoord2f(1, 0);
 126       glVertex2f(1, -1);
 127       glColor3f(1.0, 1.0, 1.0);
 128       glTexCoord2f(1, 1);
 129       glVertex2f(1, 1);
 130       glTexCoord2f(0, 1);
 131       glVertex2f(-1, 1);
 132       glEnd();
 133    }
 134
 135    glPopMatrix();
 136    glDisable(TexTarget);
 137
 138    glutSwapBuffers();
 139    CheckError(__LINE__);
 140 }
 141
 142
 143 static void
 144 Reshape(int width, int height)
 145 {
 146    glViewport(0, 0, width, height);
 147    Width = width;
 148    Height = height;
 149 }
 150
 151
 152 static void
 153 CleanUp(void)
 154 {
 155    glDeleteFramebuffersEXT(1, &MyFB);
 156
 157    glDeleteTextures(1, &TexObj);
 158
 159    glutDestroyWindow(Win);
 160
 161    exit(0);
 162 }
 163
 164
 165 static void
 166 Key(unsigned char key, int x, int y)
 167 {
 168    (void) x;
 169    (void) y;
 170    switch (key) {
 171       case 'a':
 172          Anim = !Anim;
 173          if (Anim)
 174             glutIdleFunc(Idle);
 175          else
 176             glutIdleFunc(NULL);
 177          break;
 178       case 's':
 179          Rot += 2.0;
 180          break;
 181       case 27:
 182          CleanUp();
 183          break;
 184    }
 185    glutPostRedisplay();
 186 }
 187
 188
 189 static void
 190 Init(int argc, char *argv[])
 191 {
 192    if (!glutExtensionSupported("GL_EXT_framebuffer_object")) {
 193       printf("GL_EXT_framebuffer_object not found!\n");
 194       exit(0);
 195    }
 196
 197    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 198
 199
 200    /* Make texture object/image */
 201    glGenTextures(1, &TexObj);
 202    glBindTexture(TexTarget, TexObj);
 203    glTexParameteri(TexTarget, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 204    glTexParameteri(TexTarget, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 205    glTexParameteri(TexTarget, GL_TEXTURE_BASE_LEVEL, TextureLevel);
 206    glTexParameteri(TexTarget, GL_TEXTURE_MAX_LEVEL, TextureLevel);
 207
 208    glTexImage2D(TexTarget, 0, TexIntFormat, TexWidth, TexHeight, 0,
 209                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 210
 211
 212    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 213
 214
 215
 216
 217    /* gen framebuffer id, delete it, do some assertions, just for testing */
 218    glGenFramebuffersEXT(1, &MyFB);
 219    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
 220    assert(glIsFramebufferEXT(MyFB));
 221
 222
 223    CheckError(__LINE__);
 224
 225    /* Render color to texture */
 226    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
 227                              TexTarget, TexObj, TextureLevel);
 228
 229
 230
 231    CheckError(__LINE__);
 232
 233    /* bind regular framebuffer */
 234    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 235
 236
 237 }
 238
 239
 240 int
 241 main(int argc, char *argv[])
 242 {
 243    glutInit(&argc, argv);
 244    glutInitWindowPosition(0, 0);
 245    glutInitWindowSize(Width, Height);
 246    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 247    Win = glutCreateWindow(argv[0]);
 248    glewInit();
 249    glutReshapeFunc(Reshape);
 250    glutKeyboardFunc(Key);
 251    glutDisplayFunc(Display);
 252    if (Anim)
 253       glutIdleFunc(Idle);
 254    Init(argc, argv);
 255    glutMainLoop();
 256    return 0;
 257 }