/* Rotating white cube in an environment with three colored lights, to illustrate how light color works. Modified to add a moving eye point that slides along a line from (2.0, 2.0, 10.0) to (2.0, 2.0, -10.0), always looking at the origin. As the eye moves, the cube can also be rotated in standard fashion. Example for the introductory computer graphics class; copyright ©2000, Steve Cunningham */ #include "glut.h" #include #include #include typedef GLfloat point3[3]; typedef GLfloat color [4]; typedef struct eyepoint { GLfloat x, y, z; } eyepoint; static char ch; // keyboard callback return character static GLfloat saveState[16] = {1.0,0.0,0.0,0.0, 0.0,1.0,0.0,0.0, 0.0,0.0,1.0,0.0, 0.0,0.0,0.0,1.0}, viewProj[16], // hold transforms whichway = 1.0; eyepoint ep; // function prototypes void myinit( void ); void cube( float, float, float ); void display( void ); void reshape( int ,int ); void keyboard(unsigned char, int, int ); void animate(void); void myinit(void) { // Don't define set light positions here because they must be set // in the context where the view is set GLfloat light_col0[]={ 1.0, 0.0, 0.0, 1.0 }; // light is red GLfloat amb_color0[]={ 0.3, 0.0, 0.0, 1.0 }; // even ambiently GLfloat light_col1[]={ 0.0, 1.0, 0.0, 1.0 }; // light is green GLfloat amb_color1[]={ 0.0, 0.3, 0.0, 1.0 }; // even ambiently GLfloat light_col2[]={ 0.0, 0.0, 1.0, 1.0 }; // light is blue GLfloat amb_color2[]={ 0.0, 0.0, 0.3, 1.0 }; // even ambiently GLfloat mat_specular[] ={ 0.8, 0.8, 0.8, 1.0 }; long i = 1; glClearColor( 0.0, 0.0, 0.0, 0.0 ); glShadeModel(GL_SMOOTH); glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, mat_specular ); glLightfv(GL_LIGHT0, GL_AMBIENT, amb_color0 ); glLightfv(GL_LIGHT0, GL_SPECULAR, light_col0 ); glLightfv(GL_LIGHT0, GL_DIFFUSE, light_col0 ); glLightfv(GL_LIGHT1, GL_AMBIENT, amb_color1 ); glLightfv(GL_LIGHT1, GL_SPECULAR, light_col1 ); glLightfv(GL_LIGHT1, GL_DIFFUSE, light_col1 ); glLightfv(GL_LIGHT2, GL_AMBIENT, amb_color2 ); glLightfv(GL_LIGHT2, GL_SPECULAR, light_col2 ); glLightfv(GL_LIGHT2, GL_DIFFUSE, light_col2 ); glLightModeliv(GL_LIGHT_MODEL_TWO_SIDE, &i ); // two-sided lighting // attributes glEnable(GL_LIGHTING); // so lighting models are used glEnable(GL_LIGHT0); // we'll use LIGHT0 glEnable(GL_LIGHT1); // ... and LIGHT1 glEnable(GL_LIGHT2); // ... and LIGHT2 glEnable(GL_DEPTH_TEST); // allow z-buffer display glEnable(GL_NORMALIZE); // make normal vectors 1-unit long after transform // initial eyepoint ep.x = ep.y = 2.0; ep.z = 10.0; } #include "cube.c" void display( void ) { // Light positions... GLfloat light_pos0[]={ 0.0, 10.0, 2.0, 1.0 }; // first light up y-axis GLfloat light_pos1[]={ 5.0, -5.0, 2.0, 1.0 }; // second light lower right GLfloat light_pos2[]={ -5.0, 5.0, 2.0, 1.0 }; // third light lower left // Begin with a *PARAMETRIZED* viewpoint... glMatrixMode(GL_MODELVIEW); glLoadIdentity(); // eye point center of view up gluLookAt( ep.x, ep.y, ep.z, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); // Light positions are set after the viewing transformation is defined glLightfv(GL_LIGHT0, GL_POSITION, light_pos0 ); // light 0 glLightfv(GL_LIGHT1, GL_POSITION, light_pos1 ); // light 1 glLightfv(GL_LIGHT2, GL_POSITION, light_pos2 ); // light 2 // The GL_MODELVIEW_MATRIX starts out including the viewing transformation, // so we'll first take that off, then construct the modeling transformation, // then take *THAT* off, then put them back together. Sounds a little like // Humpty-Dumpty, but... glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // We save the original viewing projection in the viewProj array glPushMatrix(); glGetFloatv( GL_MODELVIEW_MATRIX, viewProj ); // Put the identity onto the modelview stack to start the viewing transform glLoadIdentity(); #define Angle 5.0 switch(ch) { case 'q': glRotatef( Angle, 1.0, 0.0, 0.0); break; case 'w': glRotatef(-Angle, 1.0, 0.0, 0.0); break; case 'a': glRotatef( Angle, 0.0, 1.0, 0.0); break; case 's': glRotatef(-Angle, 0.0, 1.0, 0.0); break; case 'z': glRotatef( Angle, 0.0, 0.0, 1.0); break; case 'x': glRotatef(-Angle, 0.0, 0.0, 1.0); break; } ch = ' '; // NOW we apply the rest of the modeling transformation by POST-multiplying // by the saved matrix, and then save that and put the identity back on the // stack. *whew* glMultMatrixf( saveState ); glGetFloatv( GL_MODELVIEW_MATRIX, saveState ); glLoadIdentity(); // And finally rebuild the overall modelview matrix by multiplying by the // viewing transformation and then by the modeling transformation glMultMatrixf( viewProj ); glMultMatrixf( saveState ); cube(1.0,1.0,1.0); // And put ourselves back into the original GL_MODELVIEW_MATRIX by popping // off the new work. The stack again has one thing on it, and that is the // viewing transformation. glPopMatrix(); glutSwapBuffers(); } void reshape(int w,int h) { glViewport(0,0,(GLsizei)w,(GLsizei)h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(60.0,1.0,1.0,30.0); } void keyboard(unsigned char key, int x, int y) { ch = ' '; switch (key) { case 'q' : // rotate around X; i = positive, j = negative ch = key; break; case 'w' : ch = key; break; case 'a' : // rotate around Y; k = positive, m = negative ch = key; break; case 's' : ch = key; break; case 'z' : // rotate around Z; a = positive, s = negative ch = key; break; case 'x' : ch = key; break; } glutPostRedisplay(); } void animate(void) { GLfloat numsteps = 200.0, direction[3] = {0.0, 0.0, -20.0}; if (ep.z < -10.0) whichway = -1.0; if (ep.z > 10.0) whichway = 1.0; ep.z += whichway*direction[2]/numsteps; glutPostRedisplay(); } void main(int argc, char** argv) { // Standard GLUT initialization glutInit(&argc,argv); glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(500,500); glutInitWindowPosition(70,70); glutCreateWindow("A white cube with three colored lights"); glutDisplayFunc(display); glutReshapeFunc(reshape); glutKeyboardFunc(keyboard); // enable keyboard callback glutIdleFunc(animate); myinit(); glutMainLoop(); }