/* Demonstration of aliasing

Written by Caroline Geiersbach and Scott D. Anderson
scott.anderson@acm.org
Summer 2003
*/

#include <stdio.h>
#include <tw.h>
#include <math.h>

int ObjectID = 1;                // start with the teapot

void drawScene() {
    twColorName(TW_CYAN);
    switch (ObjectID) {
    case 1: glutSolidTeapot(1); break;
    case 2: glutWireCube(2); break;
    case 3: glutSolidCube(2); break;
    case 4: glutSolidSphere(1,25,25); break;
    }
}    

void display(void) {
    twDisplayInit(0,0,0);
    twCamera();
    drawScene();
    glFlush();
    glutSwapBuffers();
}

const int NumFrames = 4;

// For anti-aliasing by jittering scene location
void displayN(void) {
    glClearAccum(0,0,0,0);
    glClear(GL_ACCUM_BUFFER_BIT);
    for(int frame=0; frame<NumFrames; frame++) {
        twDisplayInit(0,0,0);        
        twCamera();
        glPushMatrix();
        // This amount is entirely made up.
        float jitter = 0.01;
        if(frame&1) glTranslatef(jitter,0,0);
        if(frame&2) glTranslatef(0,jitter,0);
        drawScene();
        glPopMatrix();
        glAccum(GL_ACCUM, 1.0/NumFrames);
    }
    // copy the scene from the accumulation buffer into the color buffer
    glAccum(GL_RETURN, 1.0);
    glFlush();
    glutSwapBuffers();
}

bool AntiAlias = false;

void keys(unsigned char k, int, int) {
    if(k > '0' && k < '9') ObjectID = k-'0';
    if(k=='a') {
        AntiAlias = !AntiAlias;
        if(AntiAlias)
            glutDisplayFunc(displayN);
        else
            glutDisplayFunc(display);
    }
    glutPostRedisplay();
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_ACCUM | GLUT_DEPTH);
    twInitWindowSize(600,600);
    glutCreateWindow(argv[0]);
    glutDisplayFunc(display);
    twBoundingBox(-2,2,-1,1,-1,1);
    twMainInit();
    twKeyCallback('a',keys,"toggle anti-aliasing");
    twKeyCallback('1',keys,"show the teapot");
    twKeyCallback('2',keys,"show the wire cube");
    twKeyCallback('3',keys,"show the solid cube");
    twKeyCallback('4',keys,"show the solid sphere");
    glutMainLoop();
    return 0;
}