The following program rotates a cube with mouse clicks. In the display callback, the Lookat function is used to point the viewer, whose location can be altered by the x, X, y, Y, z and Z keys. The perspective view is set in the reshape callback. Create the code /* cubeview.cpp */
The following program rotates a cube with mouse clicks. In the display callback, the Lookat function is used to point the viewer, whose location can be altered by the x, X, y, Y, z and Z keys. The perspective view is set in the reshape callback. Create the code
/* cubeview.cpp */
#include <stdlib.h>
#include <GL/glut.h>
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}};
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}};
GLfloat colors[][3] = {{0.0,0.0,0.0}, {0.0,0.0,1.0},
{0.0,1.0,0.0}, {0.0,1.0,1.0}, {1.0,0.0,0.0},
{1.0,0.0,1.0}, {1.0,1.0,0.0}, {1.0,1.0,1.0}};
void polygon(int a, int b, int c , int d)
{
glBegin(GL_POLYGON);
glColor3fv(colors[a]);
glNormal3fv(normals[a]);
glVertex3fv(vertices[a]);
glColor3fv(colors[b]);
glNormal3fv(normals[b]);
glVertex3fv(vertices[b]);
glColor3fv(colors[c]);
glNormal3fv(normals[c]);
glVertex3fv(vertices[c]);
glColor3fv(colors[d]);
glNormal3fv(normals[d]);
glVertex3fv(vertices[d]);
glEnd();
}
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);
}
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 */
void display()
{
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);
/* 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();
glFlush();
glutSwapBuffers();
}
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;
display();
}
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;
display();
}
void myReshape(int w, int h)
{
glViewport(0, 0, w, h);
/* Use a perspective view */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if(w<=h)
glFrustum(-2.0, 2.0, -2.0 * (GLfloat) h/ (GLfloat) w,
2.0* (GLfloat) h / (GLfloat) w, 2.0, 20.0);
else
glFrustum(-2.0, 2.0, -2.0 * (GLfloat) w/ (GLfloat) h,
2.0* (GLfloat) w / (GLfloat) h, 2.0, 20.0);
glMatrixMode(GL_MODELVIEW);
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(500, 500);
glutCreateWindow("colorcube");
glutReshapeFunc(myReshape);
glutDisplayFunc(display);
glutMouseFunc(mouse);
glutKeyboardFunc(keys);
glEnable(GL_DEPTH_TEST);
glutMainLoop();
return 0;
}
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