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/*
* Test GL_EXT_framebuffer_object render-to-texture
*
* Draw a teapot into a texture image with stenciling.
* Then draw a textured quad using that texture.
*
* Brian Paul
* 18 Apr 2005
*/
#include <GL/glew.h>
#include <GL/glut.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
/* For debug */
static int Win = 0;
static int Width = 512, Height = 512;
static GLenum TexTarget = GL_TEXTURE_2D;
static int TexWidth = 512, TexHeight = 512;
static GLuint MyFB;
static GLuint TexObj;
static GLboolean Anim = GL_FALSE;
static GLfloat Rot = 0.0;
static GLuint TextureLevel = 4; /* which texture level to render to */
static GLenum TexIntFormat = GL_RGB; /* either GL_RGB or GL_RGBA */
static void
CheckError(int line)
{
GLenum err = glGetError();
if (err) {
printf("GL Error 0x%x at line %d\n", (int) err, line);
}
}
static void
Idle(void)
{
Rot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
glutPostRedisplay();
}
static void
RenderTexture(void)
{
GLenum status;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -15.0);
if (1) {
/* draw to texture image */
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
printf("Framebuffer incomplete!!!\n");
}
glViewport(0, 0,
TexWidth / (1 << TextureLevel),
TexHeight / (1 << TextureLevel));
glClearColor(0.5, 0.5, 1.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
CheckError(__LINE__);
glBegin(GL_POLYGON);
glColor3f(1, 0, 0);
glVertex2f(-1, -1);
glColor3f(0, 1, 0);
glVertex2f(1, -1);
glColor3f(0, 0, 1);
glVertex2f(0, 1);
glEnd();
/* Bind normal framebuffer */
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
}
else {
}
CheckError(__LINE__);
}
static void
Display(void)
{
float ar = (float) Width / (float) Height;
RenderTexture();
/* draw textured quad in the window */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-ar, ar, -1.0, 1.0, 5.0, 25.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -7.0);
glViewport(0, 0, Width, Height);
glClearColor(0.25, 0.25, 0.25, 0);
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(Rot, 0, 1, 0);
glEnable(TexTarget);
glBindTexture(TexTarget, TexObj);
{
glBegin(GL_POLYGON);
glColor3f(0.25, 0.25, 0.25);
glTexCoord2f(0, 0);
glVertex2f(-1, -1);
glTexCoord2f(1, 0);
glVertex2f(1, -1);
glColor3f(1.0, 1.0, 1.0);
glTexCoord2f(1, 1);
glVertex2f(1, 1);
glTexCoord2f(0, 1);
glVertex2f(-1, 1);
glEnd();
}
glPopMatrix();
glDisable(TexTarget);
glutSwapBuffers();
CheckError(__LINE__);
}
static void
Reshape(int width, int height)
{
glViewport(0, 0, width, height);
Width = width;
Height = height;
}
static void
CleanUp(void)
{
glDeleteFramebuffersEXT(1, &MyFB);
glDeleteTextures(1, &TexObj);
glutDestroyWindow(Win);
exit(0);
}
static void
Key(unsigned char key, int x, int y)
{
(void) x;
(void) y;
switch (key) {
case 'a':
Anim = !Anim;
if (Anim)
glutIdleFunc(Idle);
else
glutIdleFunc(NULL);
break;
case 's':
Rot += 2.0;
break;
case 27:
CleanUp();
break;
}
glutPostRedisplay();
}
static void
Init(int argc, char *argv[])
{
if (!glutExtensionSupported("GL_EXT_framebuffer_object")) {
printf("GL_EXT_framebuffer_object not found!\n");
exit(0);
}
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
/* Make texture object/image */
glGenTextures(1, &TexObj);
glBindTexture(TexTarget, TexObj);
glTexParameteri(TexTarget, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(TexTarget, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(TexTarget, GL_TEXTURE_BASE_LEVEL, TextureLevel);
glTexParameteri(TexTarget, GL_TEXTURE_MAX_LEVEL, TextureLevel);
glTexImage2D(TexTarget, 0, TexIntFormat, TexWidth, TexHeight, 0,
GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glTexImage2D(TexTarget, TextureLevel, TexIntFormat,
TexWidth / (1 << TextureLevel), TexHeight / (1 << TextureLevel), 0,
GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
/* gen framebuffer id, delete it, do some assertions, just for testing */
glGenFramebuffersEXT(1, &MyFB);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, MyFB);
assert(glIsFramebufferEXT(MyFB));
CheckError(__LINE__);
/* Render color to texture */
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
TexTarget, TexObj, TextureLevel);
CheckError(__LINE__);
/* bind regular framebuffer */
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
}
int
main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(Width, Height);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
Win = glutCreateWindow(argv[0]);
glewInit();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Display);
if (Anim)
glutIdleFunc(Idle);
Init(argc, argv);
glutMainLoop();
return 0;
}
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