Pro OpenGL ES for iOS

206 CHAPTER 7: Well-Rendered Miscellany^

glClearColor(0.0, 0.0, 1.0, 1.0);

glClear(GL_COLOR_BUFFER_BIT);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

glTranslatef(0.0, (GLfloat)(sinf(transY)/2.0), z);

glRotatef(rotZ, 0, 0, 1.0); //4

glEnable(GL_TEXTURE_2D);

glBindTexture(GL_TEXTURE_2D, m_Texture.name);

glTexCoordPointer(2, GL_FLOAT,0,textureCoords1);

glEnableClientState(GL_TEXTURE_COORD_ARRAY);

glVertexPointer(3, GL_FLOAT, 0, squareVertices);

glEnableClientState(GL_VERTEX_ARRAY);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); //5

glBindFramebufferOES(GL_FRAMEBUFFER_OES, m_DefaultFBO); //6

glLoadIdentity();

glTranslatef(0.0, (GLfloat)(sinf(transY)/2.0),z);

glBindTexture(GL_TEXTURE_2D, [m_FBOController getTextureName]); //7

glClearColor(1.0, 0.0, 0.0, 1.0); //8

glClear(GL_COLOR_BUFFER_BIT);

glTexCoordPointer(2, GL_FLOAT,0,textureCoords1);

glEnableClientState(GL_TEXTURE_COORD_ARRAY);

glVertexPointer(3, GL_FLOAT, 0, fboVertices); //9

glEnableClientState(GL_VERTEX_ARRAY);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

transY += 0.075;

rotZ+=1.0;

}

„ In line 1, the vertices for the FBO are specified, not much different

from those for the bouncing image.

„ In line 2, we fetch and save the default FBO, the one used for the main

display. And if you haven’t done it yet, this should be declared as a

GLint m_Default_FBO.

„ Line 3 is where we actually tell OpenGL to use our new FBO using a

bind method not unlike those used for basic texture mapping.

Following that is the standard setup code to manage the

transformations and so on.