《基于MFC的OpenGL编程》Part 16 Reflection

 

Reflections

Adding reflections to a program too can improve its realism to a great extent. Here we'll look at a simple method to create reflection where we simply redraw the object with an appropriate transformation and make the surface in between translucent. This creates an effective illusion of reflection!!

1,设置光源代码修改如下：

void CCY457OpenGLView::SetupLighting ()
{
      //Material Properties
      GLfloat matSpecular[] = { 1.0f, 0.0f, 0.0f, 0.7f};
      GLfloat matShininess[] = { 50.0f};
      GLfloat matAmbient[] = { 0.25f, 0.25f, 0.25f, 0.7f};
      GLfloat matDiffuse[] = { 0.5f, 0.5f, 0.5f, 0.7f};
      glMaterialfv(GL_FRONT, GL_SPECULAR, matSpecular);
      glMaterialfv(GL_FRONT, GL_SHININESS, matShininess);
      glMaterialfv(GL_FRONT, GL_DIFFUSE, matDiffuse);
      glMaterialfv(GL_FRONT, GL_AMBIENT, matAmbient);
      //Lighting Parameters
      //Enable Lighting
      glEnable(GL_LIGHTING);
      //Specify a single directional light
      GLfloat ambient1[] = { 0.5f,0.5f,0.5f};
      GLfloat diffuse1[] = { 0.5f,0.5f,0.5f};
      GLfloat specular1[] = { 1.0f,0.0f,0.0f};
      GLfloat position1[] = { 0.0f,0.0f,5.0f,0.0};
      glLightfv(GL_LIGHT0, GL_AMBIENT, ambient1);
      glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse1);
      glLightfv(GL_LIGHT0, GL_SPECULAR, specular1);
      glLightfv(GL_LIGHT0, GL_POSITION, position1);    
      glEnable(GL_LIGHT0);
      //Specify a single positional spotlight
      GLfloat ambient2[] = { 1.0f,1.0f,0.0f};
      GLfloat diffuse2[] = { 1.0f,0.0f,0.0f};
      GLfloat position2[] = { 1.0f,0.0f,5.0f,1.0};
      GLfloat direction2[] = {0.0f,0.0f,-5.0f};
      glLightfv(GL_LIGHT1, GL_AMBIENT, ambient2);
      glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse2);
      glLightfv(GL_LIGHT1, GL_POSITION, position2);
      glLightfv(GL_LIGHT1, GL_SPOT_DIRECTION, direction2);
      glLightf(GL_LIGHT1, GL_SPOT_CUTOFF, 15.0f);
      glEnable(GL_LIGHT1);
}

2,绘制函数修改如下：

void CCY457OpenGLView::RenderScene ()
{//绘制函数
      glTranslatef(0.0f,0.0f,-8.0f);
      // Save matrix state and do the rotation
      glPushMatrix();
           glRotatef(m_xRot, 1.0f, 0.0f, 0.0f);
           DrawCube();
           glPopMatrix();
           glPushMatrix();
                 glTranslatef(0.0f, -3.0f, 0.0f);
                 glScalef(1.0f, -1.0f, 1.0f);
                 glRotatef(m_xRot, 1.0f, 0.0f, 0.0f);
                 DrawCube();
           glPopMatrix();
           // Draw bottom of floor
           glEnable(GL_BLEND);
           glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
           glPushMatrix();
           glEnable(GL_TEXTURE_2D);
           glBindTexture(GL_TEXTURE_2D, m_Texture[3]);
           glBegin(GL_POLYGON);
                 glTexCoord2f(0.0f, 0.0f);
                 glVertex3f(-5.0f, -1.5f, 5.0f );
                 glTexCoord2f(1.0f, 0.0f);
                 glVertex3f(-5.0f, -1.5f, -5.0f );
                 glTexCoord2f(1.0f, 1.0f);
                 glVertex3f(5.0f, -1.5f, -5.0f );
                 glTexCoord2f(0.0f, 1.0f);
                 glVertex3f(5.0f, -1.5f, 5.0f );
           glEnd();
      glPopMatrix();
      glDisable(GL_TEXTURE_2D);
      glDisable(GL_BLEND); 
}
void CCY457OpenGLView::DrawCube ()
{
           glEnable(GL_TEXTURE_2D);
           glBindTexture(GL_TEXTURE_2D,m_Texture[0]);    
           //Front Face
           glBegin(GL_POLYGON);
                 glTexCoord2f(0,0);
                 glVertex3f(-1.0f,-1.0f,0.0f);
                 glTexCoord2f(1,0);
                 glVertex3f( 1.0f,-1.0f,0.0f);
                 glTexCoord2f(1,1);
                 glVertex3f( 1.0f, 1.0f,0.0f);
                 glTexCoord2f(0,1);
                 glVertex3f(-1.0f, 1.0f,0.0f);
           glEnd();
           //Back Face
           glBegin(GL_POLYGON);
                 glTexCoord2f(1,0);
                 glVertex3f(-1.0f,-1.0f,-1.0f);
                 glTexCoord2f(1,1);
                 glVertex3f(-1.0f, 1.0f,-1.0f);
                 glTexCoord2f(0,1);
                 glVertex3f( 1.0f, 1.0f,-1.0f);
                 glTexCoord2f(0,0);
                 glVertex3f( 1.0f,-1.0f,-1.0f);
           glEnd();
           glBindTexture(GL_TEXTURE_2D,m_Texture[1]);
           //Left Face
           glBegin(GL_POLYGON);
                 glTexCoord2f(1,0);
                 glVertex3f(-1.0f,-1.0f, 0.0f);
                 glTexCoord2f(1,1);
                 glVertex3f(-1.0f, 1.0f, 0.0f);
                 glTexCoord2f(0,1);
                 glVertex3f(-1.0f, 1.0f,-1.0f);
                 glTexCoord2f(0,0);
                 glVertex3f(-1.0f,-1.0f,-1.0f);
           glEnd();
           //Right Face
           glBegin(GL_POLYGON);
                 glTexCoord2f(0,0);
                 glVertex3f(1.0f,-1.0f, 0.0f);
                 glTexCoord2f(1,0);
                 glVertex3f(1.0f,-1.0f,-1.0f);
                 glTexCoord2f(1,1);
                 glVertex3f(1.0f, 1.0f,-1.0f);
                 glTexCoord2f(0,1);
                 glVertex3f(1.0f, 1.0f, 0.0f);
           glEnd();
           glBindTexture(GL_TEXTURE_2D,m_Texture[2]);
           //Top Face
           glBegin(GL_POLYGON);
                 glTexCoord2f(0,0);
                 glVertex3f(-1.0f, 1.0f, 0.0f);
                 glTexCoord2f(0,1);
                 glVertex3f( 1.0f, 1.0f, 0.0f);
                 glTexCoord2f(1,1);
                 glVertex3f( 1.0f, 1.0f, -1.0f);
                 glTexCoord2f(1,0);
                 glVertex3f(-1.0f, 1.0f, -1.0f);
           glEnd();
           //Botton Face
           glBegin(GL_POLYGON);
                 glTexCoord2f(0,1);
                 glVertex3f(-1.0f, -1.0f, 0.0f);
                 glTexCoord2f(0,0);
                 glVertex3f(-1.0f, -1.0f, -1.0f);
                 glTexCoord2f(1,0);
                 glVertex3f( 1.0f, -1.0f, -1.0f);
                 glTexCoord2f(1,1);
                 glVertex3f( 1.0f, -1.0f, 0.0f);
           glEnd();
           glDisable(GL_TEXTURE_2D);
}