OpenGL超级宝典学习笔记——累积缓冲区与其他颜色操作

#include "gltools.h"

GLfloat fLightPos[4]   = { -100.0f, 100.0f, 50.0f, 1.0f }; 
GLfloat fNoLight[] = { 0.0f, 0.0f, 0.0f, 0.0f };
GLfloat fLowLight[] = { 0.25f, 0.25f, 0.25f, 1.0f };
GLfloat fBrightLight[] = { 1.0f, 1.0f, 1.0f, 1.0f };

static GLfloat yRot;

void DrawGround()
{
  GLfloat fExtent = 20.0f;
  GLfloat y = -0.0f;
  GLfloat step = 0.5f;

  GLfloat x, z;
int iColor = 0;
  glShadeModel(GL_FLAT);
for (x = -fExtent; x <= fExtent; x += step)
  {
    glBegin(GL_TRIANGLE_STRIP);
for (z = fExtent; z >= -fExtent; z -= step)
      {
if ((iColor % 2) == 0)
        {
          glColor4f(0.0f, 0.0f, 0.0f, 0.5f);
        }
else
        {
          glColor4f(1.0f, 1.0f, 1.0f, 0.5f);
        }
        glVertex3f(x, y, z);
        glVertex3f(x + step, y, z);

        iColor++;
      }
    glEnd();
  }
  glShadeModel(GL_SMOOTH);

}

void DrawGemometry()
{
  glPushMatrix();
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    DrawGround();

    glColor3f(1.0f, 0.0f, 0.0f);
    glTranslatef(0.0f, 0.3f, -3.5f);
    glRotatef(-yRot*2.0f, 0.0f, 1.0f, 0.0f);
    glTranslatef(1.0f, 0.0f, 0.0f);
    glutSolidSphere(0.1f, 17, 13);
  glPopMatrix();
}

void RenderScene()
{
  yRot = 35.0f;
  GLfloat pass = 10.0f;
for (int i = 0; i < 10; ++i)
  {
    yRot += 0.75f;
    DrawGemometry();

//复制到累积缓冲区
if (i == 0)
    {
      glAccum(GL_LOAD, 0.5f);
    }
else
    {
//累加到累积缓冲区
      glAccum(GL_ACCUM, (0.5f * 1 / pass));
    }
  }

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

void ChangeSize(GLsizei w, GLsizei h)
{
if (h == 0)
    h = 1;

  glViewport(0, 0, w, h);

  GLfloat faspect = (GLfloat)w/(GLfloat)h;


  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  gluPerspective(35.0f, faspect, 1.0f, 50.0f);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glTranslatef(0.0f, -0.4f, 0.0f);

  glutPostRedisplay();
}

void SetupRC()
{
  glClearColor(0.25f, 0.25f, 0.25f, 1.0f);

  glEnable(GL_DEPTH_TEST);
  glEnable(GL_CULL_FACE);
  glCullFace(GL_BACK);
  glFrontFace(GL_CCW);


//设置光照
  glLightModelfv(GL_LIGHT_MODEL_AMBIENT, fNoLight);
  glLightfv(GL_LIGHT0, GL_AMBIENT, fLowLight);
  glLightfv(GL_LIGHT0, GL_DIFFUSE, fBrightLight);
  glLightfv(GL_LIGHT0, GL_SPECULAR, fBrightLight);
  glLightfv(GL_LIGHT0, GL_POSITION, fLightPos);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);


//开启颜色追踪
  glEnable(GL_COLOR_MATERIAL);
  glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
  glMateriali(GL_FRONT, GL_SHININESS, 128);
}


int main(int args, char **argv)
{
  glutInit(&args, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE | GLUT_ACCUM);
  glutInitWindowSize(800, 600);
  glutCreateWindow("motion blur");

  glutDisplayFunc(RenderScene);
  glutReshapeFunc(ChangeSize);

  SetupRC();

  glutMainLoop();
return 0;
}