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
  10 /* For debug */
  11
  12
  13 static int Win = 0;
  14 static int Width = 512, Height = 512;
  15
  16 static GLenum TexTarget = GL_TEXTURE_2D;
  17 static int TexWidth = 512, TexHeight = 512;
  18
  19 static GLuint MyFB;
  20 static GLuint TexObj;
  21 static GLboolean Anim = GL_FALSE;
  22 static GLfloat Rot = 0.0;
  23 static GLuint TextureLevel = 4;  /* which texture level to render to */
  24 static GLenum TexIntFormat = GL_RGB; /* either GL_RGB or GL_RGBA */
  25
  26
  27 static void
  28 CheckError(int line)
  29 {
  30    GLenum err = glGetError();
  31    if (err) {
  32       printf("GL Error 0x%x at line %d\n", (int) err, line);
  33    }
  34 }
  35
  36
  37 static void
  38 Idle(void)
  39 {
  40    Rot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
  41    glutPostRedisplay();
  42 }
  43
  44
  45 static void
  46 RenderTexture(void)
  47 {
  48    GLenum status;
  49
  50    glMatrixMode(GL_PROJECTION);
  51    glLoadIdentity();
  52    glOrtho(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  53    glMatrixMode(GL_MODELVIEW);
  54    glLoadIdentity();
  55    glTranslatef(0.0, 0.0, -15.0);
  56
  57    if (1) {
  58       /* draw to texture image */
  59       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
  60
  61       status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
  62       if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
  63          printf("Framebuffer incomplete!!!\n");
  64       }
  65
  66       glViewport(0, 0,
  67                  TexWidth / (1 << TextureLevel),
  68                  TexHeight / (1 << TextureLevel));
  69       glClearColor(0.5, 0.5, 1.0, 0.0);
  70       glClear(GL_COLOR_BUFFER_BIT);
  71
  72       CheckError(__LINE__);
  73
  74       glBegin(GL_POLYGON);
  75       glColor3f(1, 0, 0);
  76       glVertex2f(-1, -1);
  77       glColor3f(0, 1, 0);
  78       glVertex2f(1, -1);
  79       glColor3f(0, 0, 1);
  80       glVertex2f(0, 1);
  81       glEnd();
  82
  83       /* Bind normal framebuffer */
  84       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
  85    }
  86    else {
  87    }
  88
  89    CheckError(__LINE__);
  90 }
  91
  92
  93
  94 static void
  95 Display(void)
  96 {
  97    float ar = (float) Width / (float) Height;
  98
  99    RenderTexture();
 100
 101    /* draw textured quad in the window */
 102    glMatrixMode(GL_PROJECTION);
 103    glLoadIdentity();
 104    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 25.0);
 105    glMatrixMode(GL_MODELVIEW);
 106    glLoadIdentity();
 107    glTranslatef(0.0, 0.0, -7.0);
 108
 109    glViewport(0, 0, Width, Height);
 110
 111    glClearColor(0.25, 0.25, 0.25, 0);
 112    glClear(GL_COLOR_BUFFER_BIT);
 113
 114    glPushMatrix();
 115    glRotatef(Rot, 0, 1, 0);
 116    glEnable(TexTarget);
 117    glBindTexture(TexTarget, TexObj);
 118
 119    {
 120       glBegin(GL_POLYGON);
 121       glColor3f(0.25, 0.25, 0.25);
 122       glTexCoord2f(0, 0);
 123       glVertex2f(-1, -1);
 124       glTexCoord2f(1, 0);
 125       glVertex2f(1, -1);
 126       glColor3f(1.0, 1.0, 1.0);
 127       glTexCoord2f(1, 1);
 128       glVertex2f(1, 1);
 129       glTexCoord2f(0, 1);
 130       glVertex2f(-1, 1);
 131       glEnd();
 132    }
 133
 134    glPopMatrix();
 135    glDisable(TexTarget);
 136
 137    glutSwapBuffers();
 138    CheckError(__LINE__);
 139 }
 140
 141
 142 static void
 143 Reshape(int width, int height)
 144 {
 145    glViewport(0, 0, width, height);
 146    Width = width;
 147    Height = height;
 148 }
 149
 150
 151 static void
 152 CleanUp(void)
 153 {
 154    glDeleteFramebuffersEXT(1, &MyFB);
 155
 156    glDeleteTextures(1, &TexObj);
 157
 158    glutDestroyWindow(Win);
 159
 160    exit(0);
 161 }
 162
 163
 164 static void
 165 Key(unsigned char key, int x, int y)
 166 {
 167    (void) x;
 168    (void) y;
 169    switch (key) {
 170       case 'a':
 171          Anim = !Anim;
 172          if (Anim)
 173             glutIdleFunc(Idle);
 174          else
 175             glutIdleFunc(NULL);
 176          break;
 177       case 's':
 178          Rot += 2.0;
 179          break;
 180       case 27:
 181          CleanUp();
 182          break;
 183    }
 184    glutPostRedisplay();
 185 }
 186
 187
 188 static void
 189 Init(int argc, char *argv[])
 190 {
 191    if (!glutExtensionSupported("GL_EXT_framebuffer_object")) {
 192       printf("GL_EXT_framebuffer_object not found!\n");
 193       exit(0);
 194    }
 195
 196    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 197
 198
 199    /* Make texture object/image */
 200    glGenTextures(1, &TexObj);
 201    glBindTexture(TexTarget, TexObj);
 202    glTexParameteri(TexTarget, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 203    glTexParameteri(TexTarget, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 204    glTexParameteri(TexTarget, GL_TEXTURE_BASE_LEVEL, TextureLevel);
 205    glTexParameteri(TexTarget, GL_TEXTURE_MAX_LEVEL, TextureLevel);
 206
 207    glTexImage2D(TexTarget, 0, TexIntFormat, TexWidth, TexHeight, 0,
 208                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 209    glTexImage2D(TexTarget, TextureLevel, TexIntFormat,
 210                 TexWidth / (1 << TextureLevel), TexHeight / (1 << TextureLevel), 0,
 211                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 212
 213
 214    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 215
 216
 217
 218
 219    /* gen framebuffer id, delete it, do some assertions, just for testing */
 220    glGenFramebuffersEXT(1, &MyFB);
 221    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
 222    assert(glIsFramebufferEXT(MyFB));
 223
 224
 225    CheckError(__LINE__);
 226
 227    /* Render color to texture */
 228    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
 229                              TexTarget, TexObj, TextureLevel);
 230
 231
 232
 233    CheckError(__LINE__);
 234
 235    /* bind regular framebuffer */
 236    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 237
 238
 239 }
 240
 241
 242 int
 243 main(int argc, char *argv[])
 244 {
 245    glutInit(&argc, argv);
 246    glutInitWindowPosition(0, 0);
 247    glutInitWindowSize(Width, Height);
 248    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 249    Win = glutCreateWindow(argv[0]);
 250    glewInit();
 251    glutReshapeFunc(Reshape);
 252    glutKeyboardFunc(Key);
 253    glutDisplayFunc(Display);
 254    if (Anim)
 255       glutIdleFunc(Idle);
 256    Init(argc, argv);
 257    glutMainLoop();
 258    return 0;
 259 }