/* lightlab.c --- Experimentation with lighting in OpenGL. * Tom Kelliher 4/2/98. * Bill Thibault 5/6/05 changed includes a bit for windoze * * Movement is via x/X, y/Y, and z/Z keys. Use space bar to exit. Mouse * buttons rotate the right cube. * * Things to try: * 1) Run program as is. Move around. Note lack of shadows and * differences between left and right cubes. * 2) Comment out the DIRTY define and verify that the cubes look * the same. Un-comment out the define when finished. * 3) In display(), swap the gluLookAt() and glLightfv() calls. Can * see any effect of doing this? Re-swap the calls when finished * 4) Try the light source at a few different positions. Can you see * any difference as a directional vs. positional source? * 5) Un-comment out the GET_VALUES define and expeiment with material * and light values. * 6) Try to find material and light values that provide realistic * looking results. (Hint: you may want to augment the code by * changing the constant, linear, and quadratic distance attenuation * coefficients. See the man page for glLight.) * 7) Add another light source. * 8) Augment the code so that each light and each object has * independent properties. */ #include #include #include #include // Vertices for right cube. GLfloat vertices[][3] = {{-1.0,-1.0,-1.0},{1.0,-1.0,-1.0}, {1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, {-1.0,-1.0,1.0}, {1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}}; // Un-comment to be queried for light and material properties. //#define GET_VALUES // Un-comment to use "quick and dirty normals" for right cube. #define DIRTY #ifdef DIRTY // These are the "quick and dirty" normals for the right cube, // 1 per vertex. GLfloat normals[][3] = {{-1.0,-1.0,-1.0},{1.0,-1.0,-1.0}, {1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, {-1.0,-1.0,1.0}, {1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}}; #else // These are the real normals for the right cube, 1 per face. GLfloat normals[][3] = {{0.0,0.0,-1.0},{0.0,1.0,0.0}, {-1.0,0.0,0.0},{1.0,0.0,0.0},{0.0,0.0,1.0},{0.0,-1.0,0.0}}; #endif // The right cube can be rotated. Whoopee. static GLfloat theta[] = {0.0,0.0,0.0}; static GLint axis = 2; static GLdouble viewer[]= {0.0, 0.0, 5.0}; /* initial viewer location */ // Guess what this one is. // Fourth parameter: 0.0 --- directional light source // 1.0 --- positional light source. GLfloat light_position[] = { 0.0, 5.0, 5.0, 0.0 }; #ifdef DIRTY // Draw a polygon with its normals. void polygon(int a, int b, int c , int d) { glBegin(GL_POLYGON); glNormal3fv(normals[a]); glVertex3fv(vertices[a]); glNormal3fv(normals[b]); glVertex3fv(vertices[b]); glNormal3fv(normals[c]); glVertex3fv(vertices[c]); glNormal3fv(normals[d]); glVertex3fv(vertices[d]); glEnd(); } // Draw a cube with lighting normals. void colorcube() { polygon(0,3,2,1); polygon(2,3,7,6); polygon(0,4,7,3); polygon(1,2,6,5); polygon(4,5,6,7); polygon(0,1,5,4); } #else // !DIRTY void polygon(int a, int b, int c , int d, GLfloat normal[]) { glBegin(GL_POLYGON); glNormal3fv(normal); glVertex3fv(vertices[a]); glVertex3fv(vertices[b]); glVertex3fv(vertices[c]); glVertex3fv(vertices[d]); glEnd(); } void colorcube() { polygon(0,3,2,1,normals[0]); polygon(2,3,7,6,normals[1]); polygon(0,4,7,3,normals[2]); polygon(1,2,6,5,normals[3]); polygon(4,5,6,7,normals[4]); polygon(0,1,5,4,normals[5]); } #endif // Paint the scene. void display(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); /* Update viewer position in modelview matrix */ glLoadIdentity(); gluLookAt(viewer[0],viewer[1],viewer[2], 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); // Position the light. glLightfv(GL_LIGHT0, GL_POSITION, light_position); glPushMatrix(); // Left cube with "correct normals." glTranslatef(-2.0, 0.0, 0.0); glutSolidCube(2.0); // Sphere centered at origin. glTranslatef(2.0, 0.0, 0.0); glutSolidSphere(1.0, 32, 32); // Right cube with normals determined by DIRTY. glTranslatef(2.0, 0.0, 0.0); // Rotate cube. glRotatef(theta[0], 1.0, 0.0, 0.0); glRotatef(theta[1], 0.0, 1.0, 0.0); glRotatef(theta[2], 0.0, 0.0, 1.0); colorcube(); // Now that I'm thoroughly confused, let's re-establish the origin. glPopMatrix(); // Up y-axis by 1. glTranslatef(0.0, 1.0, 0.0); // Rotate z-axis up to y-axis. glRotatef(-90.0, 1.0, 0.0, 0.0); glutSolidCone(1.0, 2.0, 32, 32); // Translate up the cone. glTranslatef(0.0, 0.0, 1.0); glutSolidTorus(0.25, 1.0, 32, 32); glFlush(); glutSwapBuffers(); } // Rotate the right cube. Looks kinda neat when it cuts into the sphere. void mouse(int btn, int state, int x, int y) { if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) axis = 0; if(btn==GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) axis = 1; if(btn==GLUT_RIGHT_BUTTON && state == GLUT_DOWN) axis = 2; theta[axis] += 2.0; if( theta[axis] > 360.0 ) theta[axis] -= 360.0; glutPostRedisplay(); } void keys(unsigned char key, int x, int y) { /* Use x, X, y, Y, z, and Z keys to move viewer */ if(key == 'x') viewer[0]-= 1.0; if(key == 'X') viewer[0]+= 1.0; if(key == 'y') viewer[1]-= 1.0; if(key == 'Y') viewer[1]+= 1.0; if(key == 'z') viewer[2]-= 1.0; if(key == 'Z') viewer[2]+= 1.0; if(key == ' ') exit(0); printf("v[x]: %f, v[y]: %f, v[z]: %f.\n", viewer[0], viewer[1], viewer[2]); glutPostRedisplay(); } void myReshape(int w, int h) { glViewport(0, 0, w, h); /* Use a perspective view */ glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(35.0, (GLfloat) w/h, 1.0, 100.0); glMatrixMode(GL_MODELVIEW); } // Set material and light values. void init(void) { // Default values for material and light properties. GLfloat mat_ambient[] = { 0.5, 0.0, 0.0, 1.0 }; GLfloat mat_diffuse[] = { 1.0, 0.5, 0.5, 1.0 }; GLfloat mat_specular[] = { 1.0, 0.5, 0.5, 1.0 }; GLfloat mat_shininess[] = { 50.0 }; GLfloat light_ambient[] = { 1.0, 1.0, 1.0, 1.0 }; GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 }; GLfloat light_specular[] = { 1.0, 1.0, 1.0, 1.0 }; #ifdef GET_VALUES printf("Enter RGB float values for material ambient properties: "); scanf("%f %f %f", mat_ambient, mat_ambient+1, mat_ambient+2); printf("Enter RGB float values for material diffuse properties: "); scanf("%f %f %f", mat_diffuse, mat_diffuse+1, mat_diffuse+2); printf("Enter RGB float values for material specular properties: "); scanf("%f %f %f", mat_specular, mat_specular+1, mat_specular+2); printf("Enter shininess float value: "); scanf("%f", mat_shininess); printf("Enter RGB float values for light ambient properties: "); scanf("%f %f %f", light_ambient, light_ambient+1, light_ambient+2); printf("Enter RGB float values for light diffuse properties: "); scanf("%f %f %f", light_diffuse, light_diffuse+1, light_diffuse+2); printf("Enter RGB float values for light specular properties: "); scanf("%f %f %f", light_specular, light_specular+1, light_specular+2); #endif glClearColor (0.2f, 0.3f, 0.4f, 1.0); glShadeModel (GL_SMOOTH); glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse); glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess); glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient); glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse); glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_DEPTH_TEST); glEnable(GL_NORMALIZE); /* The "quick and dirty" normals haven't been normalized. */ } void main(int argc, char **argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(500, 500); glutCreateWindow("Light Lab"); glutReshapeFunc(myReshape); glutDisplayFunc(display); glutMouseFunc(mouse); glutKeyboardFunc(keys); init(); glutMainLoop(); }