progs/trivial/tri-fbo-tex.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 <GL/glut.h>
  14 #include <assert.h>
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <math.h>
  19
  20 /* For debug */
  21
  22
  23 static int Win = 0;
  24 static int Width = 512, Height = 512;
  25
  26 static GLenum TexTarget = GL_TEXTURE_2D;
  27 static int TexWidth = 512, TexHeight = 512;
  28
  29 static GLuint MyFB;
  30 static GLuint TexObj;
  31 static GLboolean Anim = GL_FALSE;
  32 static GLfloat Rot = 0.0;
  33 static GLuint TextureLevel = 0;  /* which texture level to render to */
  34 static GLenum TexIntFormat = GL_RGB; /* either GL_RGB or GL_RGBA */
  35
  36
  37 static void
  38 CheckError(int line)
  39 {
  40    GLenum err = glGetError();
  41    if (err) {
  42       printf("GL Error 0x%x at line %d\n", (int) err, line);
  43    }
  44 }
  45
  46
  47 static void
  48 Idle(void)
  49 {
  50    Rot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
  51    glutPostRedisplay();
  52 }
  53
  54
  55 static void
  56 RenderTexture(void)
  57 {
  58    GLenum status;
  59
  60    glMatrixMode(GL_PROJECTION);
  61    glLoadIdentity();
  62    glOrtho(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  63    glMatrixMode(GL_MODELVIEW);
  64    glLoadIdentity();
  65    glTranslatef(0.0, 0.0, -15.0);
  66
  67    if (1) {
  68       /* draw to texture image */
  69       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
  70
  71       status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
  72       if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
  73          printf("Framebuffer incomplete!!!\n");
  74       }
  75
  76       glViewport(0, 0, TexWidth, TexHeight);
  77
  78       glClearColor(0.5, 0.5, 1.0, 0.0);
  79       glClear(GL_COLOR_BUFFER_BIT);
  80
  81       CheckError(__LINE__);
  82
  83       glBegin(GL_POLYGON);
  84       glColor3f(1, 0, 0);
  85       glVertex2f(-1, -1);
  86       glColor3f(0, 1, 0);
  87       glVertex2f(1, -1);
  88       glColor3f(0, 0, 1);
  89       glVertex2f(0, 1);
  90       glEnd();
  91
  92       /* Bind normal framebuffer */
  93       glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
  94    }
  95    else {
  96    }
  97
  98    CheckError(__LINE__);
  99 }
 100
 101
 102
 103 static void
 104 Display(void)
 105 {
 106    float ar = (float) Width / (float) Height;
 107
 108    RenderTexture();
 109
 110    /* draw textured quad in the window */
 111    glMatrixMode(GL_PROJECTION);
 112    glLoadIdentity();
 113    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 25.0);
 114    glMatrixMode(GL_MODELVIEW);
 115    glLoadIdentity();
 116    glTranslatef(0.0, 0.0, -7.0);
 117
 118    glViewport(0, 0, Width, Height);
 119
 120    glClearColor(0.25, 0.25, 0.25, 0);
 121    glClear(GL_COLOR_BUFFER_BIT);
 122
 123    glPushMatrix();
 124    glRotatef(Rot, 0, 1, 0);
 125    glEnable(TexTarget);
 126    glBindTexture(TexTarget, TexObj);
 127
 128    {
 129       glBegin(GL_POLYGON);
 130       glColor3f(0.25, 0.25, 0.25);
 131       glTexCoord2f(0, 0);
 132       glVertex2f(-1, -1);
 133       glTexCoord2f(1, 0);
 134       glVertex2f(1, -1);
 135       glColor3f(1.0, 1.0, 1.0);
 136       glTexCoord2f(1, 1);
 137       glVertex2f(1, 1);
 138       glTexCoord2f(0, 1);
 139       glVertex2f(-1, 1);
 140       glEnd();
 141    }
 142
 143    glPopMatrix();
 144    glDisable(TexTarget);
 145
 146    glutSwapBuffers();
 147    CheckError(__LINE__);
 148 }
 149
 150
 151 static void
 152 Reshape(int width, int height)
 153 {
 154    glViewport(0, 0, width, height);
 155    Width = width;
 156    Height = height;
 157 }
 158
 159
 160 static void
 161 CleanUp(void)
 162 {
 163    glDeleteFramebuffersEXT(1, &MyFB);
 164
 165    glDeleteTextures(1, &TexObj);
 166
 167    glutDestroyWindow(Win);
 168
 169    exit(0);
 170 }
 171
 172
 173 static void
 174 Key(unsigned char key, int x, int y)
 175 {
 176    (void) x;
 177    (void) y;
 178    switch (key) {
 179       case 'a':
 180          Anim = !Anim;
 181          if (Anim)
 182             glutIdleFunc(Idle);
 183          else
 184             glutIdleFunc(NULL);
 185          break;
 186       case 's':
 187          Rot += 2.0;
 188          break;
 189       case 27:
 190          CleanUp();
 191          break;
 192    }
 193    glutPostRedisplay();
 194 }
 195
 196
 197 static void
 198 Init(int argc, char *argv[])
 199 {
 200    static const GLfloat mat[4] = { 1.0, 0.5, 0.5, 1.0 };
 201    GLint i;
 202
 203    if (!glutExtensionSupported("GL_EXT_framebuffer_object")) {
 204       printf("GL_EXT_framebuffer_object not found!\n");
 205       exit(0);
 206    }
 207
 208    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 209
 210
 211    /* Make texture object/image */
 212    glGenTextures(1, &TexObj);
 213    glBindTexture(TexTarget, TexObj);
 214    glTexParameteri(TexTarget, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 215    glTexParameteri(TexTarget, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 216    glTexParameteri(TexTarget, GL_TEXTURE_BASE_LEVEL, TextureLevel);
 217    glTexParameteri(TexTarget, GL_TEXTURE_MAX_LEVEL, TextureLevel);
 218
 219    glTexImage2D(TexTarget, 0, TexIntFormat, TexWidth, TexHeight, 0,
 220                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 221
 222
 223    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 224
 225
 226
 227
 228    /* gen framebuffer id, delete it, do some assertions, just for testing */
 229    glGenFramebuffersEXT(1, &MyFB);
 230    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
 231    assert(glIsFramebufferEXT(MyFB));
 232
 233
 234    CheckError(__LINE__);
 235
 236    /* Render color to texture */
 237    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
 238                              TexTarget, TexObj, TextureLevel);
 239
 240
 241
 242    CheckError(__LINE__);
 243
 244    /* bind regular framebuffer */
 245    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 246
 247
 248 }
 249
 250
 251 int
 252 main(int argc, char *argv[])
 253 {
 254    glutInit(&argc, argv);
 255    glutInitWindowPosition(0, 0);
 256    glutInitWindowSize(Width, Height);
 257    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 258    Win = glutCreateWindow(argv[0]);
 259    glutReshapeFunc(Reshape);
 260    glutKeyboardFunc(Key);
 261    glutDisplayFunc(Display);
 262    if (Anim)
 263       glutIdleFunc(Idle);
 264    Init(argc, argv);
 265    glutMainLoop();
 266    return 0;
 267 }