/* Example for CS496, SDSU, Spring 2000. Based on work of Ben Eadington, student at CSU Stanislaus, Fall 1998. Used by permission This project defines an NXM array of numbers. It then constructs a grid of 3 dimensional boxes corresponding to the entries in the array. Each box has a height proportional to the number stored in its corresponding array entry. It also draws a 3 dimensional arrow pointing at the top of the highest box. */ #define PC #ifdef MAC #include "glut.h" #endif #ifdef OSX #include #endif #ifdef UNIX #include #endif #ifdef PC #include #include #include #endif #include #include #include #define PI 3.14159 #define N 5 // Number of bars in x direction #define M 6 // Number of bars in z direction typedef GLfloat point3[3]; static GLfloat angle = 0.0; GLfloat grid[N][M]; // Array to hold numbers for 3D bars. int maxX, maxZ; // Will hold the location of the maximum value in grid void myinit(void) { int i, j; int rand(); srand(time(NULL)); // Seed random number generator // initialize array to define 3D bars with random numbers between 0 and 4 // and store location of maximum value in maxX and maxZ. maxX = 0; maxZ = 0; for (i = 0; i < N; i++) for (j = 0; j < M; j++) { grid[i][j] = (rand()%40/10.0); if (grid[i][j] > grid[maxX][maxZ]) { maxX = i; maxZ = j; } } glClearColor(0.4, 0.4, 1.0, 1.0); // blue background glEnable(GL_DEPTH_TEST); // enable z buffer for hidden surface removal } // Unit cube in first octant void cube(void) { point3 cv[8] = { // Vertices of cube {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}, }; glBegin(GL_QUAD_STRIP); // Draw one quad strip glVertex3fv(cv[1]); glVertex3fv(cv[5]); glVertex3fv(cv[0]); glVertex3fv(cv[4]); glVertex3fv(cv[2]); glVertex3fv(cv[6]); glVertex3fv(cv[3]); glVertex3fv(cv[7]); glEnd(); glBegin(GL_QUAD_STRIP); // Draw second quad strip glVertex3fv(cv[0]); glVertex3fv(cv[2]); glVertex3fv(cv[1]); glVertex3fv(cv[3]); glVertex3fv(cv[5]); glVertex3fv(cv[7]); glVertex3fv(cv[4]); glVertex3fv(cv[6]); glEnd(); } void pointer(void) { point3 tip[24]; // array to hold vertices for base of tip of arrow point3 shafttop[24]; // vertices for top of arrow shaft point3 shaftbottom[24]; // vertices for bottom of arrow shaft int i; GLfloat ang = PI/12; // angle between triangle slices for (i = 0; i <= 23; i++) // calculate vertices at base of arrow tip { tip[i][0] = 0.5*cos(i*ang); tip[i][1] = 1.0; tip[i][2] = 0.5*sin(i*ang); } for (i = 0; i <= 23; i++) // calculate vertices at top and bottom of shaft { shafttop[i][0] = shaftbottom[i][0] = 0.25*cos(i*ang); shafttop[i][2] = shaftbottom[i][2] = 0.25*sin(i*ang); shafttop[i][1] = 1.0; shaftbottom[i][1] = 2.0; } glBegin(GL_TRIANGLE_FAN); // Draw tip of arrow glVertex3f(0.0, 0.0, 0.0); for (i = 0; i <= 23; i++) { glVertex3fv(tip[i]); } glVertex3fv(tip[0]); glEnd(); glBegin(GL_TRIANGLE_FAN); // Draw base of tip glVertex3f(0.0, 1.0, 0.0); for (i = 0; i <= 23; i++) { glVertex3fv(tip[i]); } glVertex3fv(tip[0]); glEnd(); glBegin(GL_QUAD_STRIP); // Draw pointer shaft for (i = 0; i <= 23; i++) { glVertex3fv(shafttop[i]); glVertex3fv(shaftbottom[i]); } glVertex3fv(shafttop[0]); glVertex3fv(shaftbottom[0]); glEnd(); glBegin(GL_TRIANGLE_FAN); // Draw base of pointer shaft glVertex3f(0.0, 2.0, 0.0); for (i = 0; i <= 23; i++) { glVertex3fv(shaftbottom[i]); } glVertex3fv(shaftbottom[0]); glEnd(); } void display( void ) { int i, j; int rand(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the window and z-buffer bit glPushMatrix(); glTranslatef(N/2.0, 0.0, M/2.0); // center of rotation is center of cube glRotatef(angle, 0.0, 1.0, 0.0); // rotate model by angle around y-axis glTranslatef(-N/2.0, 0.0, -M/2.0); for (i = N-1; i >= 0; i--) for (j = 0; j < M; j++) { glColor3f((i+j)%10/10.0, (i+2*j)%10/10.0, 0.0); // different color for each box glPushMatrix(); glTranslatef(i, 0.0, j); // move box to correct location (with grid centered at the origin) glScalef(0.9, grid[i][j], 0.9); // scale length and width for space and to scale height. cube(); // draw cube glPopMatrix(); } glPushMatrix(); glColor3f(1.0, 1.0, 1.0); // draw a white pointer glTranslatef(maxX + 0.45, grid[maxX][maxZ], maxZ + 0.45); // move arrow to correct location glRotatef(45, 1.0, 0.0, -1.0); // rotate arrow to point along the line x = y = z glScalef(0.5, 0.5, 0.5); // scale arrow down to half size pointer(); // draw arrow glPopMatrix(); glPopMatrix(); // undo last rotation you set glFlush(); glutSwapBuffers(); } void reshape(int w, int h) { glViewport(0, 0, (GLsizei)w, (GLsizei)h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(100.0, 1.0, 1.0, 3000.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); // eye point center of view up gluLookAt(-4.0, 4.0, 4.0, N/2.0, 1.5, M/2.0, 0.0, 1.0, 0.0); // view is from outside the grid along the line x = -y = -z } void animate(void) { angle += 3; // update angle for rotation in display glutPostRedisplay(); // perform display again } void main(int argc, char** argv) { // Standard GLUT initialization glutInit(&argc,argv); glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); // Double buffering, RGB color, z-buffer set glutInitWindowSize(500,500); // 500 x 500 pixel window glutInitWindowPosition(50,50); // window near top left of display glutCreateWindow("Project 1 - 3D Bars"); // window title glutDisplayFunc(display); // display callback when window opened glutReshapeFunc(reshape); // viewing the displayed object glutIdleFunc(animate); // do this when other activity absent myinit(); // set attributes glutMainLoop(); // enter event loop }