/* * Warp a triangle mesh with a vertex program. */ #include <assert.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <math.h> #define GL_GLEXT_PROTOTYPES #include <GL/glut.h> static float Xrot = -60.0, Yrot = 0.0, Zrot = 0.0; static GLboolean Anim = GL_TRUE; static GLfloat Phi = 0.0; static void Idle( void ) { Phi += 0.01; glutPostRedisplay(); } static void DrawMesh( int rows, int cols ) { static const GLfloat colorA[3] = { 0, 1, 0 }; static const GLfloat colorB[3] = { 0, 0, 1 }; const float dx = 2.0 / (cols - 1); const float dy = 2.0 / (rows - 1); float x, y; int i, j; #if 1 #define COLOR3FV(c) glVertexAttrib3fvARB(3, c) #define VERTEX2F(x, y) glVertexAttrib2fARB(0, x, y) #else #define COLOR3FV(c) glColor3fv(c) #define VERTEX2F(x, y) glVertex2f(x, y) #endif y = -1.0; for (i = 0; i < rows - 1; i++) { glBegin(GL_QUAD_STRIP); x = -1.0; for (j = 0; j < cols; j++) { if ((i + j) & 1) COLOR3FV(colorA); else COLOR3FV(colorB); VERTEX2F(x, y); VERTEX2F(x, y + dy); x += dx; } glEnd(); y += dy; } } static void Display( void ) { glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); glPushMatrix(); glRotatef(Xrot, 1, 0, 0); glRotatef(Yrot, 0, 1, 0); glRotatef(Zrot, 0, 0, 1); /* Position the gravity source */ { GLfloat x, y, z, r = 0.5; x = r * cos(Phi); y = r * sin(Phi); z = 1.0; glProgramLocalParameter4fARB(GL_VERTEX_PROGRAM_ARB, 30, x, y, z, 1); glDisable(GL_VERTEX_PROGRAM_ARB); glBegin(GL_POINTS); glColor3f(1,1,1); glVertex3f(x, y, z); glEnd(); } glEnable(GL_VERTEX_PROGRAM_ARB); DrawMesh(8, 8); glPopMatrix(); glutSwapBuffers(); } static void Reshape( int width, int height ) { float ar = (float) width / (float) height; glViewport( 0, 0, width, height ); glMatrixMode( GL_PROJECTION ); glLoadIdentity(); glFrustum( -1.0 * ar, 1.0 * ar, -1.0, 1.0, 5.0, 25.0 ); glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glTranslatef( 0.0, 0.0, -12.0 ); glScalef(2, 2, 2); } 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 'p': Phi += 0.2; break; case 'z': Zrot -= 5.0; break; case 'Z': Zrot += 5.0; break; case 27: exit(0); break; } glutPostRedisplay(); } static void SpecialKey( int key, int x, int y ) { const GLfloat step = 3.0; (void) x; (void) y; switch (key) { case GLUT_KEY_UP: Xrot -= step; break; case GLUT_KEY_DOWN: Xrot += step; break; case GLUT_KEY_LEFT: Yrot -= step; break; case GLUT_KEY_RIGHT: Yrot += step; break; } glutPostRedisplay(); } static void Init( void ) { GLuint prognum; GLint errno; /* * c[0..3] = modelview matrix * c[4..7] = inverse modelview matrix * c[30] = gravity source location * c[31] = gravity source strength * c[32] = light pos * c[35] = diffuse color */ static const char prog[] = "!!ARBvp1.0\n" "TEMP R1, R2, R3; " "# Compute distance from vertex to gravity source\n" "ADD R1, program.local[30], -vertex.position; # vector from vertex to gravity\n" "DP3 R2, R1, R1; # dot product\n" "RSQ R2, R2.x; # square root = distance\n" "MUL R2, R2, program.local[31].xxxx; # scale by the gravity factor\n" "# Displace vertex by gravity factor along R1 vector\n" "MAD R3, R1, R2, vertex.position;\n" "# Continue with typical modelview/projection\n" "DP4 result.position.x, state.matrix.mvp.row[0], R3 ; # object x MVP -> clip\n" "DP4 result.position.y, state.matrix.mvp.row[1], R3 ;\n" "DP4 result.position.z, state.matrix.mvp.row[2], R3 ;\n" "DP4 result.position.w, state.matrix.mvp.row[3], R3 ;\n" "MOV result.color, vertex.color;\n # copy input color to output color\n" "END"; if (!glutExtensionSupported("GL_ARB_vertex_program")) { printf("Sorry, this program requires GL_ARB_vertex_program\n"); exit(1); } glGenProgramsARB(1, &prognum); glBindProgramARB(GL_VERTEX_PROGRAM_ARB, prognum); glProgramStringARB(GL_VERTEX_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB, strlen(prog), (const GLubyte *)prog); errno = glGetError(); printf("glGetError = %d\n", errno); if (errno != GL_NO_ERROR) { GLint errorpos; glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorpos); printf("errorpos: %d\n", errorpos); printf("%s\n", glGetString(GL_PROGRAM_ERROR_STRING_ARB)); } /* Light position */ glProgramLocalParameter4fARB(GL_VERTEX_PROGRAM_ARB, 32, 2, 2, 4, 1); /* Diffuse material color */ glProgramLocalParameter4fARB(GL_VERTEX_PROGRAM_ARB, 35, 0.25, 0, 0.25, 1); /* Gravity strength */ glProgramLocalParameter4fARB(GL_VERTEX_PROGRAM_ARB, 31, .5, 0, 0, 0); glEnable(GL_DEPTH_TEST); glClearColor(0.3, 0.3, 0.3, 1); glShadeModel(GL_FLAT); glPointSize(3); } int main( int argc, char *argv[] ) { glutInit( &argc, argv ); glutInitWindowPosition( 0, 0 ); glutInitWindowSize( 250, 250 ); glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH ); glutCreateWindow(argv[0]); glutReshapeFunc( Reshape ); glutKeyboardFunc( Key ); glutSpecialFunc( SpecialKey ); glutDisplayFunc( Display ); if (Anim) glutIdleFunc(Idle); Init(); glutMainLoop(); return 0; }