progs/trivial/tri-fbo-tex-mip.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 = 4;  /* 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,
  69                  TexWidth / (1 << TextureLevel),
  70                  TexHeight / (1 << TextureLevel));
  71       glClearColor(0.5, 0.5, 1.0, 0.0);
  72       glClear(GL_COLOR_BUFFER_BIT);
  73
  74       CheckError(__LINE__);
  75
  76       glBegin(GL_POLYGON);
  77       glColor3f(1, 0, 0);
  78       glVertex2f(-1, -1);
  79       glColor3f(0, 1, 0);
  80       glVertex2f(1, -1);
  81       glColor3f(0, 0, 1);
  82       glVertex2f(0, 1);
  83       glEnd();
  84
  85       /* Bind normal framebuffer */
  86       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
  87    }
  88    else {
  89    }
  90
  91    CheckError(__LINE__);
  92 }
  93
  94
  95
  96 static void
  97 Display(void)
  98 {
  99    float ar = (float) Width / (float) Height;
 100
 101    RenderTexture();
 102
 103    /* draw textured quad in the window */
 104    glMatrixMode(GL_PROJECTION);
 105    glLoadIdentity();
 106    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 25.0);
 107    glMatrixMode(GL_MODELVIEW);
 108    glLoadIdentity();
 109    glTranslatef(0.0, 0.0, -7.0);
 110
 111    glViewport(0, 0, Width, Height);
 112
 113    glClearColor(0.25, 0.25, 0.25, 0);
 114    glClear(GL_COLOR_BUFFER_BIT);
 115
 116    glPushMatrix();
 117    glRotatef(Rot, 0, 1, 0);
 118    glEnable(TexTarget);
 119    glBindTexture(TexTarget, TexObj);
 120
 121    {
 122       glBegin(GL_POLYGON);
 123       glColor3f(0.25, 0.25, 0.25);
 124       glTexCoord2f(0, 0);
 125       glVertex2f(-1, -1);
 126       glTexCoord2f(1, 0);
 127       glVertex2f(1, -1);
 128       glColor3f(1.0, 1.0, 1.0);
 129       glTexCoord2f(1, 1);
 130       glVertex2f(1, 1);
 131       glTexCoord2f(0, 1);
 132       glVertex2f(-1, 1);
 133       glEnd();
 134    }
 135
 136    glPopMatrix();
 137    glDisable(TexTarget);
 138
 139    glutSwapBuffers();
 140    CheckError(__LINE__);
 141 }
 142
 143
 144 static void
 145 Reshape(int width, int height)
 146 {
 147    glViewport(0, 0, width, height);
 148    Width = width;
 149    Height = height;
 150 }
 151
 152
 153 static void
 154 CleanUp(void)
 155 {
 156    glDeleteFramebuffersEXT(1, &MyFB);
 157
 158    glDeleteTextures(1, &TexObj);
 159
 160    glutDestroyWindow(Win);
 161
 162    exit(0);
 163 }
 164
 165
 166 static void
 167 Key(unsigned char key, int x, int y)
 168 {
 169    (void) x;
 170    (void) y;
 171    switch (key) {
 172       case 'a':
 173          Anim = !Anim;
 174          if (Anim)
 175             glutIdleFunc(Idle);
 176          else
 177             glutIdleFunc(NULL);
 178          break;
 179       case 's':
 180          Rot += 2.0;
 181          break;
 182       case 27:
 183          CleanUp();
 184          break;
 185    }
 186    glutPostRedisplay();
 187 }
 188
 189
 190 static void
 191 Init(int argc, char *argv[])
 192 {
 193    if (!glutExtensionSupported("GL_EXT_framebuffer_object")) {
 194       printf("GL_EXT_framebuffer_object not found!\n");
 195       exit(0);
 196    }
 197
 198    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 199
 200
 201    /* Make texture object/image */
 202    glGenTextures(1, &TexObj);
 203    glBindTexture(TexTarget, TexObj);
 204    glTexParameteri(TexTarget, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 205    glTexParameteri(TexTarget, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 206    glTexParameteri(TexTarget, GL_TEXTURE_BASE_LEVEL, TextureLevel);
 207    glTexParameteri(TexTarget, GL_TEXTURE_MAX_LEVEL, TextureLevel);
 208
 209    glTexImage2D(TexTarget, 0, TexIntFormat, TexWidth, TexHeight, 0,
 210                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 211    glTexImage2D(TexTarget, TextureLevel, TexIntFormat,
 212                 TexWidth / (1 << TextureLevel), TexHeight / (1 << TextureLevel), 0,
 213                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 214
 215
 216    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 217
 218
 219
 220
 221    /* gen framebuffer id, delete it, do some assertions, just for testing */
 222    glGenFramebuffersEXT(1, &MyFB);
 223    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
 224    assert(glIsFramebufferEXT(MyFB));
 225
 226
 227    CheckError(__LINE__);
 228
 229    /* Render color to texture */
 230    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
 231                              TexTarget, TexObj, TextureLevel);
 232
 233
 234
 235    CheckError(__LINE__);
 236
 237    /* bind regular framebuffer */
 238    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 239
 240
 241 }
 242
 243
 244 int
 245 main(int argc, char *argv[])
 246 {
 247    glutInit(&argc, argv);
 248    glutInitWindowPosition(0, 0);
 249    glutInitWindowSize(Width, Height);
 250    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 251    Win = glutCreateWindow(argv[0]);
 252    glewInit();
 253    glutReshapeFunc(Reshape);
 254    glutKeyboardFunc(Key);
 255    glutDisplayFunc(Display);
 256    if (Anim)
 257       glutIdleFunc(Idle);
 258    Init(argc, argv);
 259    glutMainLoop();
 260    return 0;
 261 }