// Render to Texture Example // Create Texture from Sierpinski Gasket // Diffuse this texture // Add random points ieach iteration and diffuse them #include "Angel.h" using namespace std; const int NumTimesToSubdivide = 5; const int NumTriangles = 243; // 3^5 triangles generated const int NumVertices = 3 * NumTriangles; const int TEXSIZE=512; vec2 points[NumVertices]; // points for Sierpinski gasket // Two triangles for quad to draw texture in // quad[6] extra point used to add random points dynamically vec2 quad[7] = {vec2(-1.0, -1.0), vec2(-1.0, 1.0), vec2(1.0, 1.0), vec2(1.0, 1.0), vec2(1.0, -1.0), vec2(-1.0, -1.0), vec2(0.0, 0.0)}; // texture coordinares for quad vec2 tex[6] = {vec2(0.0, 0.0), vec2(0.0, 1.0), vec2(1.0, 1.0), vec2(1.0, 1.0), vec2(1.0, 0.0), vec2(0.0, 0.0)}; int Index = 0; int texbuffer = 1; GLuint program1, program2, program3; GLuint framebuffer, textures[2]; GLuint renderbuffer; GLuint buffer; GLuint vao; // Sierpinski gasket functions //---------------------------------------------------------------------------- void triangle( const vec2& a, const vec2& b, const vec2& c ) { points[Index++] = a; points[Index++] = b; points[Index++] = c; } //---------------------------------------------------------------------------- void divide_triangle( const vec2& a, const vec2& b, const vec2& c, int count ) { if ( count > 0 ) { vec2 v0 = ( a + b ) / 2.0; vec2 v1 = ( a + c ) / 2.0; vec2 v2 = ( b + c ) / 2.0; divide_triangle( a, v0, v1, count - 1 ); divide_triangle( c, v1, v2, count - 1 ); divide_triangle( b, v2, v0, count - 1 ); } else { triangle( a, b, c ); // draw triangle at end of recursion } } //---------------------------------------------------------------------------- void init( void ) { glPointSize(10.0); glGenTextures( 2, textures); glBindTexture(GL_TEXTURE_2D, textures[0]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, TEXSIZE, TEXSIZE, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST ); glBindTexture(GL_TEXTURE_2D, textures[1]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, TEXSIZE, TEXSIZE, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST ); glEnable(GL_TEXTURE_2D); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, textures[1]); glGenRenderbuffers(1, &renderbuffer); glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer); glGenFramebuffers( 1, &framebuffer); glBindFramebuffer( GL_DRAW_FRAMEBUFFER, framebuffer); glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textures[1], 0); vec2 vertices[3] = { vec2( -1.0, -1.0 ), vec2( 0.0, 1.0 ), vec2( 1.0, -1.0 ) }; // Subdivide the original triangle divide_triangle( vertices[0], vertices[1], vertices[2], NumTimesToSubdivide ); // Create vertex array objects glGenVertexArraysAPPLE( 1, &vao ); glBindVertexArrayAPPLE( vao ); // Create and initialize a buffer object glGenBuffers( 1, &buffer ); glBindBuffer( GL_ARRAY_BUFFER, buffer ); glBufferData( GL_ARRAY_BUFFER, sizeof(points), NULL, GL_STATIC_DRAW ); glBufferSubData( GL_ARRAY_BUFFER, 0, sizeof(points), points); // Load shaders program1 = InitShader( "vrender21.glsl", "frender21.glsl" ); program2 = InitShader( "vrender22.glsl", "frender22.glsl" ); program3 = InitShader( "vrender23.glsl", "frender23.glsl" ); // Initialize the vertex position attribute from the vertex shader glClearColor( 1.0, 1.0, 1.0, 1.0 ); /* white background */ } //---------------------------------------------------------------------------- void display( void ) { // render into render buffer glUseProgram( program1 ); // Initialize the vertex position attribute from the vertex shader GLuint loc = glGetAttribLocation( program1, "vPosition" ); glEnableVertexAttribArray( loc ); glVertexAttribPointer( loc, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) ); glBindBuffer( GL_ARRAY_BUFFER, buffer); glBindFramebuffer(GL_DRAW_FRAMEBUFFER, framebuffer); glViewport(0, 0, TEXSIZE, TEXSIZE); glClearColor(1.0, 1.0, 1.0, 1.0); glClear( GL_COLOR_BUFFER_BIT ); glDrawArrays( GL_TRIANGLES, 0, 3*NumTriangles ); // Bind to window system frame buffer, unbind the texture glGenerateMipmap(GL_TEXTURE_2D); glBindFramebuffer(GL_FRAMEBUFFER, 0); glBufferData(GL_ARRAY_BUFFER, sizeof(quad)+sizeof(tex), NULL, GL_STATIC_DRAW); glBufferSubData( GL_ARRAY_BUFFER, 0, sizeof(quad), quad); glBufferSubData( GL_ARRAY_BUFFER, sizeof(quad), sizeof(tex), tex); glUseProgram(program2); glDisableVertexAttribArray(loc); GLuint quad_loc = glGetAttribLocation( program2, "vPosition" ); glEnableVertexAttribArray( quad_loc ); glVertexAttribPointer( quad_loc, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) ); GLuint vTexCoord = glGetAttribLocation( program2, "vTexCoord"); glEnableVertexAttribArray( vTexCoord ); glVertexAttribPointer( vTexCoord, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(sizeof(quad)) ); GLuint quad_loc3 = glGetAttribLocation( program3, "vPosition" ); glEnableVertexAttribArray( quad_loc3 ); glVertexAttribPointer( quad_loc3, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) ); glUniform1i( glGetUniformLocation(program2, "texture"), 0 ); glUniform1f( glGetUniformLocation(program2, "d"), 1.0/((float) TEXSIZE ) ); glBindTexture(GL_TEXTURE_2D, textures[1]); glViewport(0, 0, TEXSIZE, TEXSIZE); glClearColor(0.0, 0.0, 0.0, 1.0); glClear( GL_COLOR_BUFFER_BIT ); glDrawArrays( GL_TRIANGLES, 0, 6 ); glutSwapBuffers(); } //--------------------------------------------------------------------------- void idle( void) { // uncomment for frame by frame display // int s; //scanf("%d",&s); // render to texture glBindTexture(GL_TEXTURE_2D, textures[texbuffer]); glGenRenderbuffers(1, &renderbuffer); glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer); glGenFramebuffers( 1, &framebuffer); glBindFramebuffer( GL_DRAW_FRAMEBUFFER, framebuffer); glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textures[1-texbuffer], 0); glDrawArrays( GL_TRIANGLES, 0, 6 ); // drop in a random point using program 3 glUseProgram(program3); float rx = 2.0*rand()/RAND_MAX-1.0; float ry = 2.0*rand()/RAND_MAX-1.0; quad[6] = vec2(rx, ry); glBufferSubData( GL_ARRAY_BUFFER, 0, sizeof(quad), quad); glDrawArrays(GL_POINTS, 6, 1); glUseProgram(program2); // render to display glGenerateMipmap(GL_TEXTURE_2D); glBindFramebuffer(GL_FRAMEBUFFER, 0); glBindTexture(GL_TEXTURE_2D, textures[1-texbuffer]); glViewport(0, 0, TEXSIZE, TEXSIZE); glClearColor(1.0, 0.0, 0.0, 1.0); glClear( GL_COLOR_BUFFER_BIT ); glDrawArrays( GL_TRIANGLES, 0, 6 ); glutSwapBuffers(); // swap textures if(texbuffer==1) texbuffer = 0; else texbuffer = 1; } //---------------------------------------------------------------------------- void keyboard( unsigned char key, int x, int y ) { switch ( key ) { case 033: case 'q': case 'Q': exit( EXIT_SUCCESS ); break; } } //---------------------------------------------------------------------------- int main( int argc, char **argv ) { glutInit( &argc, argv ); glutInitDisplayMode( GLUT_RGBA |GLUT_DOUBLE); glutInitWindowSize( TEXSIZE, TEXSIZE ); glutCreateWindow( "Simple GLSL example" ); init(); glutDisplayFunc( display ); glutKeyboardFunc( keyboard ); glutIdleFunc(idle); glutMainLoop(); return 0; }