motion_blur.cpp

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#include <GL/glut.h>
#include <GL/glu.h>
#include <stdlib.h>
#include <math.h>

#define PI_ 3.14159265358979323846


// File a modified to show the motion blur effect on the gold teapot.
// The idea of applied technique is taken both from OpenGL red book
// and "Advanced Graphics Programming Techniques Using OpenGL", section 9.1.
// Then we render the scene with moving object N times (with N distinct
// positions of the object) appending them into accumulation buffer.
// The current position of the teapot is rendered more sharp (value provided to
// glAccum(GL_ACCUM, ...) is greater), and the previous ones more smooth.
// This is defined by the array "parts", which is calculated in init() function.
// With selected constants (0.25 and 0.75) effect looks very good, but 
// works very slow due to the large number of points (by default N = 10).
// Decreasing variable "dangle", which is incrementation of angle, makes
// motion blur more natural. By default it is small enough (1 deg).
// User can change the speed of rotation and  pause the demo. In fact 
// increasing the speed doesn't mean run faster, but rotate to the greater
// angle (more precise, dangle * speed).

#include <stdio.h>


//focus
float z = 5.0;


//number of intermediate points in motion blur
#define N  10

float parts[N];

//speed of rotation
int speed = 1;

float dangle = 1.0f;

//stop the rotation
bool pause = false;

//rotation variables
float AngleX=90;
float PrevAngleX = 90;


int LastTime = 0;
int TimerDelay = 50;
float FPS = 0;

GLuint teapotList;

/* accFrustum()
 * The first 6 arguments are identical to the glFrustum() call.
 *  
 * pixdx and pixdy are anti-alias jitter in pixels. 
 * Set both equal to 0.0 for no anti-alias jitter.
 * eyedx and eyedy are depth-of field jitter in pixels. 
 * Set both equal to 0.0 for no depth of field effects.
 *
 * focus is distance from eye to plane in focus. 
 * focus must be greater than, but not equal to 0.0.
 *
 * Note that accFrustum() calls glTranslatef().  You will 
 * probably want to insure that your ModelView matrix has been 
 * initialized to identity before calling accFrustum().
 */
void accFrustum(GLdouble left, GLdouble right, GLdouble bottom, 
   GLdouble top, GLdouble near, GLdouble far, GLdouble pixdx, 
   GLdouble pixdy, GLdouble eyedx, GLdouble eyedy, GLdouble focus)
{
   GLdouble xwsize, ywsize; 
   GLdouble dx, dy;
   GLint viewport[4];

   glGetIntegerv (GL_VIEWPORT, viewport);
        
   xwsize = right - left;
   ywsize = top - bottom;
        
   dx = -(pixdx*xwsize/(GLdouble) viewport[2] + eyedx*near/focus);
   dy = -(pixdy*ywsize/(GLdouble) viewport[3] + eyedy*near/focus);
        
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glFrustum (left + dx, right + dx, bottom + dy, top + dy, near, far);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef (-eyedx, -eyedy, 0.0);
}

/*  accPerspective()
 * 
 *  The first 4 arguments are identical to the gluPerspective() call.
 *  pixdx and pixdy are anti-alias jitter in pixels. 
 *  Set both equal to 0.0 for no anti-alias jitter.
 *  eyedx and eyedy are depth-of field jitter in pixels. 
 *  Set both equal to 0.0 for no depth of field effects.
 *
 *  focus is distance from eye to plane in focus. 
 *  focus must be greater than, but not equal to 0.0.
 *
 *  Note that accPerspective() calls accFrustum().
 */
void accPerspective(GLdouble fovy, GLdouble aspect, 
   GLdouble near, GLdouble far, GLdouble pixdx, GLdouble pixdy, 
   GLdouble eyedx, GLdouble eyedy, GLdouble focus)
{
   GLdouble fov2,left,right,bottom,top;

   fov2 = ((fovy*M_PI) / 180.0) / 2.0;

   top = near / (cos(fov2) / sin(fov2));
   bottom = -top;

   right = top * aspect;
   left = -right;

   accFrustum (left, right, bottom, top, near, far,
               pixdx, pixdy, eyedx, eyedy, focus);
}

void init(void)
{
parts[N-1] = 1.0f/N;
float sum;
for (int i = (N-2); i>=0; i--)
    {
    sum = parts[i+1] + 1.0f/N;
    parts[i+1] = .25 * sum;
    parts[i]   = .75 * sum;
    }
printf(" Accumulation portions are defined as follows: \n");
for (int i= 0; i<N; i++)
    {
    printf("\tparts[%d] = %f \n", i, parts[i]);
    }

GLenum performance = GL_FASTEST; //GL_NICEST
glHint(GL_POINT_SMOOTH_HINT, performance );
glHint(GL_LINE_SMOOTH_HINT, performance );
glHint(GL_POLYGON_SMOOTH_HINT, performance );
glHint(GL_FOG_HINT, performance );
glHint(GL_PERSPECTIVE_CORRECTION_HINT, performance );

/*
  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LESS);
  glShadeModel(GL_SMOOTH);
  glEnable(GL_LIGHTING);
  glDisable( GL_CULL_FACE );
  glEnable( GL_NORMALIZE );
  */
   GLfloat ambient[] = { 0.0, 0.0, 0.0, 1.0 };
   GLfloat diffuse[] = { 1.0, 1.0, 1.0, 1.0 };
   GLfloat specular[] = { 1.0, 1.0, 1.0, 1.0 };
   GLfloat position[] = { 0.0, 3.0, 3.0, 0.0 };
    
   GLfloat lmodel_ambient[] = { 0.2, 0.2, 0.2, 1.0 };
   GLfloat local_view[] = { 0.0 };

   glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
   glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
   glLightfv(GL_LIGHT0, GL_POSITION, position);
    
   glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
   glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);

   glFrontFace (GL_CW);
   glEnable(GL_LIGHTING);
   glEnable(GL_LIGHT0);
   glEnable(GL_AUTO_NORMAL);
   glEnable(GL_NORMALIZE);
   glEnable(GL_DEPTH_TEST);

   glClearColor(0.0, 0.0, 0.0, 0.0);
   glClearAccum(0.0, 0.0, 0.0, 0.0); 
/*  make teapot display list */
   teapotList = glGenLists(1);
   glNewList (teapotList, GL_COMPILE);
   glutSolidTeapot (0.5);
   glEndList ();
}

void renderTeapot (GLfloat x, GLfloat y, GLfloat z, 
   GLfloat ambr, GLfloat ambg, GLfloat ambb, 
   GLfloat difr, GLfloat difg, GLfloat difb, 
   GLfloat specr, GLfloat specg, GLfloat specb, GLfloat shine)
{
   GLfloat mat[4];

   glPushMatrix();
   glTranslatef (x, y, z);
   mat[0] = ambr; mat[1] = ambg; mat[2] = ambb; mat[3] = 1.0;   
   glMaterialfv (GL_FRONT, GL_AMBIENT, mat);
   mat[0] = difr; mat[1] = difg; mat[2] = difb; 
   glMaterialfv (GL_FRONT, GL_DIFFUSE, mat);
   mat[0] = specr; mat[1] = specg; mat[2] = specb;
   glMaterialfv (GL_FRONT, GL_SPECULAR, mat);
   glMaterialf (GL_FRONT, GL_SHININESS, shine*128.0);
   glCallList(teapotList);
   glPopMatrix();
}

/*  display() draws 5 teapots into the accumulation buffer 
 *  several times; each time with a jittered perspective.
 *  The focal point is at z = 5.0, so the gold teapot will 
 *  stay in focus.  The amount of jitter is adjusted by the
 *  magnitude of the accPerspective() jitter; in this example, 0.33.
 *  In this example, the teapots are drawn 8 times.  See jitter.h
 */
void display(void)
{
   int jitter;
   GLint viewport[4];
GLfloat mat[4];


   glClearColor(0.0, 0.0, 0.0, 0.0);
   glClearAccum(0.0, 0.0, 0.0, 0.0); 

   glGetIntegerv (GL_VIEWPORT, viewport);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_ACCUM_BUFFER_BIT);

//then the whole scene with moving teapot at different positions
float angle;

for (int i=0; i<N; i++)
    {
//  glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
//    angle = AngleX - (AngleX - PrevAngleX)*(i)/(N) ;
        angle = PrevAngleX - i*dangle*speed;
    
    glPushMatrix();
      accPerspective (45.0, 
         (GLdouble) viewport[2]/(GLdouble) viewport[3], 
         1.0, 15.0, 0.0, 0.0,
         0, 0, 5.0);

glPushMatrix();

      renderTeapot (-1.1, -0.5, -4.5, 0.1745, 0.01175, 
                    0.01175, 0.61424, 0.04136, 0.04136, 
                    0.727811, 0.626959, 0.626959, 0.6);
glPopMatrix();


glPushMatrix();
      renderTeapot (0.2, -0.5, -5.5, 0.19225, 0.19225, 
                    0.19225, 0.50754, 0.50754, 0.50754, 
                    0.508273, 0.508273, 0.508273, 0.4);
glPopMatrix();
glPushMatrix();
      renderTeapot (1.0, -0.5, -6.0, 0.0215, 0.1745, 0.0215, 
                    0.07568, 0.61424, 0.07568, 0.633, 
                    0.727811, 0.633, 0.6);
glPopMatrix();

glPushMatrix();
      renderTeapot (1.8, -0.5, -6.5, 0.0, 0.1, 0.06, 0.0, 
                    0.50980392, 0.50980392, 0.50196078, 
                    0.50196078, 0.50196078, .25);
    glPopMatrix();

    glPushMatrix();
    glTranslatef(-0.5, -0.5, -5);
    glRotated(angle, 0, 1, 0);
       mat[0] = 0.24725; mat[1] = 0.1995; mat[2] = 0.0745; mat[3] = 1.0;        
       glMaterialfv (GL_FRONT, GL_AMBIENT, mat);
       mat[0] = 0.75164; mat[1] = 0.60648; mat[2] = 0.22648;    
       glMaterialfv (GL_FRONT, GL_DIFFUSE, mat);
       mat[0] = 0.628281; mat[1] = 0.555802; mat[2] = 0.366065;
       glMaterialfv (GL_FRONT, GL_SPECULAR, mat);
       glMaterialf (GL_FRONT, GL_SHININESS, 0.4*128.0);
       glCallList(teapotList);

    glPopMatrix();
glPopMatrix();

       glAccum (GL_ACCUM, parts[i]);
      }//endfor

if (!pause)
    PrevAngleX = PrevAngleX + speed*dangle;      


 glAccum(GL_RETURN, 1.0f);
   glutSwapBuffers();
}

void reshape(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glutPostRedisplay();
}

void keyboard(unsigned char key, int x, int y)
{
   switch (key) {
      case 27:
      case 'q':
         exit(0);
         break;
          case ' ':
                 pause = ! pause;
                 break;
          case '1':
            speed = 1;
            break;
          case '2':
            speed = 2;
            break;
          case '3':
            speed = 3;
            break;
          case '4':
            speed = 4 ;
            break;
          case '5':
            speed = 5;
            break;
          case '6':
            speed = 6;
            break;
          case '7':
            speed = 7;
            break;
          case '8':
            speed = 8;
            break;
          case '9':
            speed = 9;
            break;
          
   }
}

static void timerCallback(int)
{

int nc = glutGet(GLUT_ELAPSED_TIME);
float fSec = float(nc-LastTime) / 1000.0f;
  // Compute average frame rate from the last twenty frames
  FPS = (19.0f*FPS + 1.0f / fSec) / 20.0f;
  LastTime = nc;
  
  float fCamArc = fSec * 180.0f;
  
if (!pause)
    {
//  AngleX += fCamArc/60.0f*speed;
    AngleX += speed * dangle;
    }
    else
    {
    AngleX = PrevAngleX;
    }
  
  glutPostRedisplay();
  glutTimerFunc(TimerDelay, timerCallback, 0);

}



/*  Main Loop
 *  Be certain you request an accumulation buffer.
 */

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

printf(" Keys: \n");
printf("\tSpace -- stop moving the teapot \n");
printf("\t1..9  -- adjust speed of teapot\n");
printf("\tq     -- Quit.\n");

   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB
                        | GLUT_ACCUM | GLUT_DEPTH); 
   glutInitWindowSize (400, 400);
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   init();
   glutReshapeFunc(reshape);
   glutDisplayFunc(display);
   glutKeyboardFunc(keyboard);
   LastTime = glutGet (GLUT_ELAPSED_TIME );
   glutTimerFunc ( TimerDelay, timerCallback, 0);
   glutMainLoop();
   return 0;
}

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