/* gs_simple.c - OpenGL-based introductory geometry shader example using a pass-through geometry shader to draw a pattern of colored stars. */ /* Requires the OpenGL Utility Toolkit (GLUT) and Cg runtime (version 2.0 or higher). */ #include <stdio.h> /* for printf and NULL */ #include <stdlib.h> /* for exit */ #include <math.h> /* for sin and cos */ #if __APPLE__ #include <GLUT/glut.h> #else #include <GL/glut.h> #endif #include <Cg/cg.h> /* Can't include this? Is Cg Toolkit installed! */ #include <Cg/cgGL.h> static CGcontext myCgContext; static CGprofile myCgVertexProfile, myCgGeometryProfile, myCgFragmentProfile; static CGprogram myCgVertexProgram = 0, myCgGeometryProgram = 0, myCgFragmentProgram = 0, myCgCombinedProgram = 0; /* For combined GLSL program */ static const char *myProgramName = "gs_simple", *myVertexProgramFileName = "gs_simple.cg", *myVertexProgramName = "vertex_passthru", *myGeometryProgramFileName = "gs_simple.cg", *myGeometryProgramName = "geometry_passthru", *myFragmentProgramFileName = "gs_simple.cg", *myFragmentProgramName = "fragment_passthru"; static void checkForCgError(const char *situation) { CGerror error; const char *string = cgGetLastErrorString(&error); if (error != CG_NO_ERROR) { printf("%s: %s: %s\n", myProgramName, situation, string); if (error == CG_COMPILER_ERROR) { printf("%s\n", cgGetLastListing(myCgContext)); } exit(1); } } /* Forward declared GLUT callbacks registered by main. */ static void display(void); static void keyboard(unsigned char c, int x, int y); int main(int argc, char **argv) { glutInitWindowSize(400, 400); glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH); glutInit(&argc, argv); glutCreateWindow(myProgramName); glutDisplayFunc(display); glutKeyboardFunc(keyboard); glClearColor(0.1, 0.3, 0.6, 0.0); /* Blue background */ myCgContext = cgCreateContext(); cgGLSetDebugMode( CG_FALSE ); cgSetParameterSettingMode(myCgContext, CG_DEFERRED_PARAMETER_SETTING); checkForCgError("creating context"); myCgGeometryProfile = cgGLGetLatestProfile(CG_GL_GEOMETRY); if (myCgGeometryProfile == CG_PROFILE_UNKNOWN) { if ( cgGLIsProfileSupported(CG_PROFILE_GLSLG) ) myCgGeometryProfile = CG_PROFILE_GLSLG; else { fprintf(stderr, "%s: geometry profile is not available.\n", myProgramName); exit(0); } } cgGLSetOptimalOptions(myCgGeometryProfile); checkForCgError("selecting geometry profile"); myCgGeometryProgram = cgCreateProgramFromFile( myCgContext, /* Cg runtime context */ CG_SOURCE, /* Program in human-readable form */ myGeometryProgramFileName, /* Name of file containing program */ myCgGeometryProfile, /* Profile: OpenGL ARB geometry program */ myGeometryProgramName, /* Entry function name */ NULL); /* No extra compiler options */ checkForCgError("creating geometry program from file"); myCgVertexProfile = cgGLGetLatestProfile(CG_GL_VERTEX); if (myCgGeometryProfile == CG_PROFILE_GLSLG) { myCgVertexProfile = CG_PROFILE_GLSLV; } cgGLSetOptimalOptions(myCgVertexProfile); checkForCgError("selecting vertex profile"); myCgVertexProgram = cgCreateProgramFromFile( myCgContext, /* Cg runtime context */ CG_SOURCE, /* Program in human-readable form */ myVertexProgramFileName, /* Name of file containing program */ myCgVertexProfile, /* Profile: OpenGL ARB vertex program */ myVertexProgramName, /* Entry function name */ NULL); /* No extra compiler options */ checkForCgError("creating vertex program from file"); myCgFragmentProfile = cgGLGetLatestProfile(CG_GL_FRAGMENT); if (myCgGeometryProfile == CG_PROFILE_GLSLG) { myCgFragmentProfile = CG_PROFILE_GLSLF; } cgGLSetOptimalOptions(myCgFragmentProfile); checkForCgError("selecting fragment profile"); myCgFragmentProgram = cgCreateProgramFromFile( myCgContext, /* Cg runtime context */ CG_SOURCE, /* Program in human-readable form */ myFragmentProgramFileName, /* Name of file containing program */ myCgFragmentProfile, /* Profile: OpenGL ARB fragment program */ myFragmentProgramName, /* Entry function name */ NULL); /* No extra compiler options */ checkForCgError("creating fragment program from file"); if ( myCgVertexProfile==CG_PROFILE_GLSLV && myCgGeometryProfile==CG_PROFILE_GLSLG && myCgFragmentProfile==CG_PROFILE_GLSLF ) { /* Combine programs for GLSL... */ myCgCombinedProgram = cgCombinePrograms3(myCgVertexProgram,myCgGeometryProgram,myCgFragmentProgram); checkForCgError("combining programs"); cgGLLoadProgram(myCgCombinedProgram); checkForCgError("loading combined program"); } else { /* ...otherwise load programs orthogonally */ cgGLLoadProgram(myCgVertexProgram); checkForCgError("loading vertex program"); cgGLLoadProgram(myCgGeometryProgram); checkForCgError("loading geometry program"); cgGLLoadProgram(myCgFragmentProgram); checkForCgError("loading fragment program"); } glutMainLoop(); return 0; } static void drawStar(float x, float y, int starPoints, float R, float r, GLfloat *color) { int i; double piOverStarPoints = 3.14159 / starPoints, angle = 0.0; glBegin(GL_TRIANGLE_FAN); glColor3f(1,1,1); glVertex2f(x, y); /* Center of star */ glColor3fv(color); /* Emit exterior vertices for star's points. */ for (i=0; i<starPoints; i++) { glVertex2f(x + R*cos(angle), y + R*sin(angle)); angle += piOverStarPoints; glVertex2f(x + r*cos(angle), y + r*sin(angle)); angle += piOverStarPoints; } /* End by repeating first exterior vertex of star. */ angle = 0; glVertex2f(x + R*cos(angle), y + R*sin(angle)); glEnd(); } static void drawStars(void) { static GLfloat red[] = { 1, 0, 0 }, green[] = { 0, 1, 0 }, blue[] = { 0, 0, 1 }, cyan[] = { 0, 1, 1 }, yellow[] = { 1, 1, 0 }, gray[] = { 0.5f, 0.5f, 0.5f }; /* star outer inner */ /* x y Points radius radius */ /* ===== ===== ====== ====== ====== */ drawStar(-0.1, 0, 5, 0.5, 0.2, red); drawStar(-0.84, 0.1, 5, 0.3, 0.12, green); drawStar( 0.92, -0.5, 5, 0.25, 0.11, blue); drawStar( 0.3, 0.97, 5, 0.3, 0.1, cyan); drawStar( 0.94, 0.3, 5, 0.5, 0.2, yellow); drawStar(-0.97, -0.8, 5, 0.6, 0.2, gray); } static void display(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); cgGLEnableProfile(myCgVertexProfile); checkForCgError("enabling vertex profile"); cgGLEnableProfile(myCgGeometryProfile); checkForCgError("enabling geometry profile"); cgGLEnableProfile(myCgFragmentProfile); checkForCgError("enabling fragment profile"); if (myCgCombinedProgram) { cgGLBindProgram(myCgCombinedProgram); checkForCgError("binding combined program"); } else { cgGLBindProgram(myCgVertexProgram); checkForCgError("binding vertex program"); cgGLBindProgram(myCgGeometryProgram); checkForCgError("binding geometry program"); cgGLBindProgram(myCgFragmentProgram); checkForCgError("binding fragment program"); } drawStars(); cgGLDisableProfile(myCgVertexProfile); checkForCgError("disabling vertex profile"); cgGLDisableProfile(myCgGeometryProfile); checkForCgError("disabling geometry profile"); cgGLDisableProfile(myCgFragmentProfile); checkForCgError("disabling fragment profile"); glutSwapBuffers(); } static void keyboard(unsigned char c, int x, int y) { switch (c) { case 27: /* Esc key */ /* Demonstrate proper deallocation of Cg runtime data structures. Not strictly necessary if we are simply going to exit. */ cgDestroyProgram(myCgVertexProgram); cgDestroyProgram(myCgGeometryProgram); cgDestroyProgram(myCgFragmentProgram); if (myCgCombinedProgram) cgDestroyProgram(myCgCombinedProgram); cgDestroyContext(myCgContext); exit(0); break; } }