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