glutBasics.c

/*
 *  glutBasics.cpp
 *  GLUTTest
 *
 *  Created by GGS on June 17 2003.
 *  Copyright (c) 2003 Apple. All rights reserved.
 *
 
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                WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
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                PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN
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                IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR
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 */
 
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
 
#include <GLUT/glut.h>
#include <OpenGL/glext.h>
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
 
#include "trackball.h"
#include "SurfaceGeometry.h"
 
#define DTOR 0.0174532925
#define CROSSPROD(p1,p2,p3) \
   p3.x = p1.y*p2.z - p1.z*p2.y; \
   p3.y = p1.z*p2.x - p1.x*p2.z; \
   p3.z = p1.x*p2.y - p1.y*p2.x
   
#ifndef MIN
    #define MIN(a, b) ((a) < (b) ? (a) : (b))
#endif
 
enum {
    kTextureSize = 256
};
 
typedef struct {
   GLdouble x,y,z;
} recVec;
 
typedef struct {
    recVec viewPos; // View position
    recVec viewDir; // View direction vector
    recVec viewUp; // View up direction
    recVec rotPoint; // Point to rotate about
    GLdouble focalLength; // Focal Length along view direction
    GLdouble aperture; // gCamera aperture
    GLdouble eyeSep; // Eye separation
    GLint screenWidth,screenHeight; // current window/screen height and width
} recCamera;
 
GLfloat gShapeSize = 11.0f;
 
GLint gDollyPanStartPoint[2] = {0, 0};
GLfloat gTrackBallRotation [4] = {0.0, 0.0, 0.0, 0.0};
GLboolean gDolly = GL_FALSE;
GLboolean gPan = GL_FALSE;
GLboolean gTrackBall = GL_FALSE;
GLfloat gWorldRotation [4] = {155.0, 0.0, -1.0, 0.0};
 
GLboolean gLines = GL_FALSE;
GLboolean gPolygons = GL_TRUE;
 
GLboolean gShowHelp = GL_TRUE;
GLboolean gShowInfo = GL_TRUE;
 
recCamera gCamera;
recVec gOrigin = {0.0, 0.0, 0.0};
 
int gLastKey = ' ';
 
int gMainWindow = 0;
 
GLuint gPointList = NULL;
GLuint gWireList = NULL;
GLuint gSolidList = NULL;
 
#pragma mark ---- gCamera control ----
 
void gCameraReset(void)
{
   gCamera.aperture = 40;
   gCamera.focalLength = 15;
   gCamera.rotPoint = gOrigin;
 
   gCamera.viewPos.x = 0.0;
   gCamera.viewPos.y = 0.0;
   gCamera.viewPos.z = -gCamera.focalLength;
   gCamera.viewDir.x = -gCamera.viewPos.x; 
   gCamera.viewDir.y = -gCamera.viewPos.y; 
   gCamera.viewDir.z = -gCamera.viewPos.z;
 
   gCamera.viewUp.x = 0;  
   gCamera.viewUp.y = 1; 
   gCamera.viewUp.z = 0;
}
 
#pragma mark ---- Utilities ----
 
void
drawGLString(GLfloat x, GLfloat y, char *string)
{
  int len, i;
 
  glRasterPos2f(x, y);
  len = (int) strlen(string);
  for (i = 0; i < len; i++) {
    glutBitmapCharacter(GLUT_BITMAP_HELVETICA_10, string[i]);
  }
}
 
 
#pragma mark ---- Drawing ----
 
 
void SetLighting(unsigned int mode)
{
    GLfloat mat_specular[] = {1.0, 1.0, 1.0, 1.0};
    GLfloat mat_shininess[] = {90.0};
 
    GLfloat position[4] = {7.0,-7.0,12.0,0.0};
    GLfloat ambient[4]  = {0.2,0.2,0.2,1.0};
    GLfloat diffuse[4]  = {1.0,1.0,1.0,1.0};
    GLfloat specular[4] = {1.0,1.0,1.0,1.0};
    
    glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, mat_specular);
    glMaterialfv (GL_FRONT_AND_BACK, GL_SHININESS, mat_shininess);
    
    glEnable(GL_COLOR_MATERIAL);
    glColorMaterial(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE);
 
    switch (mode) {
        case 0:
            break;
        case 1:
            glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_FALSE);
            glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,GL_FALSE);
            break;
        case 2:
            glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_FALSE);
            glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,GL_TRUE);
            break;
        case 3:
            glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
            glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,GL_FALSE);
            break;
        case 4:
            glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
            glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,GL_TRUE);
            break;
    }
    
    glLightfv(GL_LIGHT0,GL_POSITION,position);
    glLightfv(GL_LIGHT0,GL_AMBIENT,ambient);
    glLightfv(GL_LIGHT0,GL_DIFFUSE,diffuse);
    glLightfv(GL_LIGHT0,GL_SPECULAR,specular);
    glEnable(GL_LIGHT0);
}
 
void drawGLText (GLint window_width, GLint window_height)
{
    char outString [256] = "";
    GLint matrixMode;
    GLint vp[4];
    GLint lineSpacing = 13;
    GLint line = 0;
    GLint startOffest = 7;
    
    glGetIntegerv(GL_VIEWPORT, vp);
    glViewport(0, 0, window_width, window_height);
    
    glGetIntegerv(GL_MATRIX_MODE, &matrixMode);
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();
    
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
    glScalef(2.0f / window_width, -2.0f / window_height, 1.0f);
    glTranslatef(-window_width / 2.0f, -window_height / 2.0f, 0.0f);
    
    // draw 
    glDisable(GL_LIGHTING);
    glColor3f (1.0, 1.0, 1.0);
    if (gShowInfo) {
    
        sprintf (outString, "Camera Position: (%0.1f, %0.1f, %0.1f)", gCamera.viewPos.x, gCamera.viewPos.y, gCamera.viewPos.z);
        drawGLString (10, window_height - (lineSpacing * line++) - startOffest, outString);
        sprintf (outString, "Trackball Rotation: (%0.1f, %0.2f, %0.2f, %0.2f)", gTrackBallRotation[0], gTrackBallRotation[1], gTrackBallRotation[2], gTrackBallRotation[3]);
        drawGLString (10, window_height - (lineSpacing * line++) - startOffest, outString);
        sprintf (outString, "World Rotation: (%0.1f, %0.2f, %0.2f, %0.2f)", gWorldRotation[0], gWorldRotation[1], gWorldRotation[2], gWorldRotation[3]);
        drawGLString (10, window_height - (lineSpacing * line++) - startOffest, outString);
        sprintf (outString, "Aperture: %0.1f", gCamera.aperture);
        drawGLString (10, window_height - (lineSpacing * line++) - startOffest, outString);
        sprintf (outString, "Focus Distance: %0.1f", gCamera.focalLength);
        drawGLString (10, window_height - (lineSpacing * line++) - startOffest, outString);
    }
    
    if (gShowHelp) {
        line = 1;
        sprintf (outString, "Controls:\n");
        drawGLString (10, (lineSpacing * line++) + startOffest, outString);
        sprintf (outString, "left button drag: rotate camera\n");
        drawGLString (10, (lineSpacing * line++) + startOffest, outString);
        sprintf (outString, "right (or crtl-left) button drag: dolly (zoom) camera\n");
        drawGLString (10, (lineSpacing * line++) + startOffest, outString);
        sprintf (outString, "arrows: aperture & focal length\n");
        drawGLString (10, (lineSpacing * line++) + startOffest, outString);
        sprintf (outString, "H: toggle help\n");
        drawGLString (10, (lineSpacing * line++) + startOffest, outString);
        sprintf (outString, "I: toggle info\n");
        drawGLString (10, (lineSpacing * line++) + startOffest, outString);
        sprintf (outString, "W: toggle wire frame\n");
        drawGLString (10, (lineSpacing * line++) + startOffest, outString);
    }
    
    glPopMatrix();
    glMatrixMode(GL_PROJECTION);
    glPopMatrix();
    glMatrixMode(matrixMode);
    
    glViewport(vp[0], vp[1], vp[2], vp[3]);
}
 
#pragma mark ---- GLUT callbacks ----
 
void init (void)
{
    glEnable(GL_DEPTH_TEST);
 
    glShadeModel(GL_SMOOTH);    
    glFrontFace(GL_CCW);
 
    glColor3f(1.0,1.0,1.0);
 
    BuildGeometry (kTranguloidTrefoil, 4, 64, 3, &gSolidList, &gWireList, &gPointList);
    
    glClearColor(0.0,0.0,0.0,0.0);         /* Background recColor */
    gCameraReset ();
    
    glPolygonOffset (1.0, 1.0);
    SetLighting(4);
    glEnable(GL_LIGHTING);
    
}
 
void reshape (int w, int h)
{
    glViewport(0,0,(GLsizei)w,(GLsizei)h);
    gCamera.screenWidth = w;
    gCamera.screenHeight = h;
    glutPostRedisplay();
}
 
void maindisplay(void)
{
    GLdouble xmin, xmax, ymin, ymax;
    // far frustum plane
    GLdouble zFar = -gCamera.viewPos.z + gShapeSize * 0.5;
    // near frustum plane clamped at 1.0
    GLdouble zNear = MIN (-gCamera.viewPos.z - gShapeSize * 0.5, 1.0);
    // window aspect ratio
    GLdouble aspect = gCamera.screenWidth / (GLdouble)gCamera.screenHeight; 
 
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
 
    if (aspect > 1.0) {
        ymax = zNear * tan (gCamera.aperture * 0.5 * DTOR);
        ymin = -ymax;
        xmin = ymin * aspect;
        xmax = ymax * aspect;
    } else {
        xmax = zNear * tan (gCamera.aperture * 0.5 * DTOR);
        xmin = -xmax;
        ymin = xmin / aspect;
        ymax = xmax / aspect;
    }
    glFrustum(xmin, xmax, ymin, ymax, zNear, zFar);
    
    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();
    gluLookAt (gCamera.viewPos.x, gCamera.viewPos.y, gCamera.viewPos.z,
            gCamera.viewPos.x + gCamera.viewDir.x,
            gCamera.viewPos.y + gCamera.viewDir.y,
            gCamera.viewPos.z + gCamera.viewDir.z,
            gCamera.viewUp.x, gCamera.viewUp.y ,gCamera.viewUp.z);
            
    // track ball rotation
    glRotatef (gTrackBallRotation[0], gTrackBallRotation[1], gTrackBallRotation[2], gTrackBallRotation[3]);
    glRotatef (gWorldRotation[0], gWorldRotation[1], gWorldRotation[2], gWorldRotation[3]);
    
    glClearColor (0.2f, 0.2f, 0.4f, 1.0f);  // clear the surface
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    if (gLines) {
        glColor3f (1.0, 1.0, 1.0); // no coloring
        glDisable(GL_LIGHTING);
        glCallList (gWireList);
    }
    if (gPolygons) {
        glEnable(GL_LIGHTING);
        glCallList (gSolidList);
    }
    
    drawGLText (gCamera.screenWidth, gCamera.screenHeight);
 
    glutSwapBuffers();
}
 
void special(int key, int px, int py)
{
  gLastKey = key;
  switch (key) {
    case GLUT_KEY_UP: // arrow forward, close in on world
        gCamera.focalLength -= 0.5f;
        if (gCamera.focalLength < 0.0f)
            gCamera.focalLength = 0.0f;
        glutPostRedisplay();
        break;
    case GLUT_KEY_DOWN: // arrow back, back away from world
        gCamera.focalLength += 0.5f;
        glutPostRedisplay();
        break;
    case GLUT_KEY_LEFT: // arrow left, smaller aperture
        gCamera.aperture -= 0.5f;
        if (gCamera.aperture < 0.0f)
            gCamera.aperture = 0.0f;
        glutPostRedisplay();
        break;
    case GLUT_KEY_RIGHT: // arrow right, larger aperture
        gCamera.aperture += 0.5f;
        glutPostRedisplay();
        break;
  }
}
 
void mouseDolly (int x, int y)
{
    if (gDolly) {
        GLfloat dolly = (gDollyPanStartPoint[1] - y) * -gCamera.viewPos.z / 200.0f;
        GLfloat eyeRelative = gCamera.eyeSep / gCamera.focalLength;
        gCamera.focalLength += gCamera.focalLength / gCamera.viewPos.z * dolly; 
        if (gCamera.focalLength < 1.0)
            gCamera.focalLength = 1.0;
        gCamera.eyeSep = gCamera.focalLength * eyeRelative;
        gCamera.viewPos.z += dolly;
        if (gCamera.viewPos.z == 0.0) // do not let z = 0.0
            gCamera.viewPos.z = 0.0001;
        gDollyPanStartPoint[0] = x;
        gDollyPanStartPoint[1] = y;
        glutPostRedisplay();
    }
}
 
void mousePan (int x, int y)
{
    if (gPan) {
        GLfloat panX = (gDollyPanStartPoint[0] - x) / (900.0f / -gCamera.viewPos.z);
        GLfloat panY = (gDollyPanStartPoint[1] - y) / (900.0f / -gCamera.viewPos.z);
        gCamera.viewPos.x -= panX;
        gCamera.viewPos.y -= panY;
        gDollyPanStartPoint[0] = x;
        gDollyPanStartPoint[1] = y;
        glutPostRedisplay();
    }
}
 
void mouseTrackball (int x, int y)
{
    if (gTrackBall) {
        rollToTrackball (x, y, gTrackBallRotation);
        glutPostRedisplay();
    }
}
 
void mouse (int button, int state, int x, int y)
{
    if ((button == GLUT_LEFT_BUTTON) && (state == GLUT_DOWN)) {
        if (gDolly) { // if we are currently dollying, end dolly
            mouseDolly (x, y);
            gDolly = GL_FALSE;
            glutMotionFunc (NULL);
            gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
            glutMotionFunc (NULL);
        } else if (gPan) {
            mousePan (x, y);
            gPan = GL_FALSE;
            glutMotionFunc (NULL);
            gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
            glutMotionFunc (NULL);
        }
        startTrackball (x, y, 0, 0, gCamera.screenWidth, gCamera.screenHeight);
        glutMotionFunc (mouseTrackball);
        gTrackBall = GL_TRUE;
    } else if ((button == GLUT_LEFT_BUTTON) && (state == GLUT_UP)) {
        gTrackBall = GL_FALSE;
        glutMotionFunc (NULL);
        rollToTrackball (x, y, gTrackBallRotation);
        if (gTrackBallRotation[0] != 0.0)
            addToRotationTrackball (gTrackBallRotation, gWorldRotation);
        gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
    }
    else if ((button == GLUT_RIGHT_BUTTON) && (state == GLUT_DOWN)) {
        if (gTrackBall) {// if we are currently trackballing, end trackball
            gTrackBall = GL_FALSE;
            glutMotionFunc (NULL);
            rollToTrackball (x, y, gTrackBallRotation);
            if (gTrackBallRotation[0] != 0.0)
                addToRotationTrackball (gTrackBallRotation, gWorldRotation);
            gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
        } else if (gPan) {
            mousePan (x, y);
            gPan = GL_FALSE;
            glutMotionFunc (NULL);
            gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
            glutMotionFunc (NULL);
        }
        gDollyPanStartPoint[0] = x;
        gDollyPanStartPoint[1] = y;
        glutMotionFunc (mouseDolly);
        gDolly = GL_TRUE;
    } else if ((button == GLUT_RIGHT_BUTTON) && (state == GLUT_UP)) {
        mouseDolly (x, y);
        gDolly = GL_FALSE;
        glutMotionFunc (NULL);
        gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
        glutMotionFunc (NULL);
    }
    else if ((button == GLUT_MIDDLE_BUTTON) && (state == GLUT_DOWN)) {
        if (gTrackBall) {// if we are currently trackballing, end trackball
            gTrackBall = GL_FALSE;
            glutMotionFunc (NULL);
            rollToTrackball (x, y, gTrackBallRotation);
            if (gTrackBallRotation[0] != 0.0)
                addToRotationTrackball (gTrackBallRotation, gWorldRotation);
            gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
        } else if (gDolly) {
            mouseDolly (x, y);
            gDolly = GL_FALSE;
            glutMotionFunc (NULL);
            gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
            glutMotionFunc (NULL);
        }
        gDollyPanStartPoint[0] = x;
        gDollyPanStartPoint[1] = y;
        glutMotionFunc (mousePan);
        gPan = GL_TRUE;
    } else if ((button == GLUT_MIDDLE_BUTTON) && (state == GLUT_UP)) {
        mousePan (x, y);
        gPan = GL_FALSE;
        glutMotionFunc (NULL);
        gTrackBallRotation [0] = gTrackBallRotation [1] = gTrackBallRotation [2] = gTrackBallRotation [3] = 0.0f;
        glutMotionFunc (NULL);
    }
}
 
void key(unsigned char inkey, int px, int py)
{
  gLastKey = inkey;
  switch (inkey) {
    case 27:
        exit(0);
        break;
    case 'h': // help
    case 'H':
        gShowHelp =  1 - gShowHelp;
        glutPostRedisplay();
        break;
    case 'i': // info
    case 'I':
        gShowInfo =  1 - gShowInfo;
        glutPostRedisplay();
        break;
    case 'w': // toggle wire
    case 'W':
        gLines = 1 - gLines;
        gPolygons = 1 - gPolygons;
        glutPostRedisplay();
        break;
  }
}
 
void spaceballmotion (int x, int y, int z)
{
    long deadZone = 105;
    float scale = -gCamera.viewPos.z * 0.00000001f;
    if (abs (x) > deadZone) {
        GLfloat panX = abs (x) * x * scale;
        gCamera.viewPos.x += panX;
    }
    if (abs (y) > deadZone) {
        GLfloat panY = abs (y) * y * scale;
        gCamera.viewPos.y -= panY;
    }
    if (abs (z) > deadZone) {
        GLfloat dolly = abs (z) * z * scale;
        gCamera.viewPos.z += dolly;
        if (gCamera.viewPos.z == 0.0) // do not let z = 0.0
            gCamera.viewPos.z = 0.0001;
    }
    glutPostRedisplay();
}
 
void spaceballrotate (int rx, int ry, int rz)
{
    long deadZone = 60;
    float rotation[4] = {0.0f, 0.0f, 0.0f, 0.0f};
    // handle rotations about each respective axis
    if (abs (rx) > deadZone) {
        rotation[0] = abs (rx) * -rx * 0.0000008f;
        rotation[1] = 1.0f;
        rotation[2] = 0.0f;
        rotation[3] = 0.0f;
        addToRotationTrackball (rotation, gWorldRotation);
    }
    if (abs (ry) > deadZone) {
        rotation[0] = abs (ry) * ry * 0.0000008f;
        rotation[1] = 0.0f;
        rotation[2] = 1.0f;
        rotation[3] = 0.0f;
        addToRotationTrackball (rotation, gWorldRotation);
    }
    if (abs(rz) > deadZone) {
        rotation[0] = abs (rz) * -rz * 0.0000008f;
        rotation[1] = 0.0f;
        rotation[2] = 0.0f;
        rotation[3] = 1.0f;
        addToRotationTrackball (rotation, gWorldRotation);
    }
    glutPostRedisplay();
}
 
#pragma mark ---- main ----
 
int main (int argc, const char * argv[])
{
    glutInit(&argc, (char **)argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); // non-stereo for main window
    glutInitWindowPosition (300, 50);
    glutInitWindowSize (800, 600);
    gMainWindow = glutCreateWindow("GLUT Basics");
 
    init(); // standard GL init
 
    glutReshapeFunc (reshape);
    glutDisplayFunc (maindisplay);
    glutKeyboardFunc (key);
    glutSpecialFunc (special);
    glutMouseFunc (mouse);
    glutSpaceballMotionFunc(spaceballmotion);
    glutSpaceballRotateFunc(spaceballrotate);
    glutMainLoop();
    return 0;
}