CG and Visualisation Lab(10CSL67) Vtu prg-3

/* Lab Program 3 */ /* Program to draw a color cube and spin it using OpenGL transformation matrices */

#include <stdlib.h>

#include <GL/glut.h>

// GLOBAL VARIABLES

/*cube is centered at origin */

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}};

/*colors are assigned to the vertices */

GLfloat colors[][3] = {{0.0,0.0,0.0},{1.0,0.0,0.0}, {0.0,1.0,0.0}, {0.0,0.0,1.0}, {1.0,1.0,0.0},{1.0,0.0,1.0}, {0.0,1.0,1.0},{1.0,1.0,1.0} };

static GLfloat theta[] = {0.0,0.0,0.0};\

static GLint axis = 2;

void polygon(int a, int b, int c, int d) {

/* draw a polygon via list of vertices */

glBegin(GL_POLYGON);

glColor3fv(colors[a]);

glVertex3fv(vertices[a]);

glColor3fv(colors[b]);

glVertex3fv(vertices[b]);

glColor3fv(colors[c]);

glVertex3fv(vertices[c]);

glColor3fv(colors[d]);

glVertex3fv(vertices[d]);

glEnd();

}

void colorcube() {

/* map vertices to faces */

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);

}

void display() {

/* display callback, clear frame buffer and z buffer, rotate cube and draw, swap buffers */

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glLoadIdentity();

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();

glFlush();

glutSwapBuffers();

}

void spinCube() {

/* idle callback, spin cube 2 degrees about selected axis */

theta[axis] += 2.0;

if( theta[axis] > 360.0 ) theta[axis] -= 360.0;

glutPostRedisplay();

/* Whenever circumstances indicate that your window is in need of being redisplayed, you may callÂglutPostRedisplay() to tell OpenGLUT that you want to redraw your graphics. Multiple calls to this function may be coalesced by OpenGLUT to avoid excessive invocation of your drawing support. The ultimate effect of this function is to call your Display callback for the current window. */

}

void mouse(int btn, int state, int x, int y) {

/* mouse callback, selects an axis about which to rotate */

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;

}

void myReshape(int w, int h) {

glViewport(0, 0, w, h);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

if (w <= h) glOrtho(-2.0, 2.0, -2.0 * (GLfloat) h / (GLfloat) w, 2.0 * (GLfloat) h / (GLfloat) w, -10.0, 10.0); else glOrtho(-2.0 * (GLfloat) w / (GLfloat) h, 2.0 * (GLfloat) w / (GLfloat) h, -2.0, 2.0, -10.0, 10.0); glMatrixMode(GL_MODELVIEW); }

int main(int argc, char **argv) {

glutInit(&argc, argv);

/* need both double buffering and z buffer */

glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);

glutInitWindowSize(500, 500);

glutCreateWindow("colorcube");

glutReshapeFunc(myReshape);

glutDisplayFunc(display);

glutIdleFunc(spinCube);

glutMouseFunc(mouse);

glEnable(GL_DEPTH_TEST);

/* Enable hidden-surface removal */

glutMainLoop();

}

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