Pro OpenGL ES for iOS

292 CHAPTER 9: Performance ’n’ Stuff^

So, how do we use VBOs? Very easily. Take a look at the executeVBO() method in

Listing 9-2.

Listing 9-2. Rendering the Planet Using VBOs

-(bool)executeVBO

{

int i;

static int counter=0;

glBindBuffer(GL_ARRAY_BUFFER, m_VBO_SphereDataName); //1

glMatrixMode(GL_MODELVIEW);

glDisable(GL_CULL_FACE); //2

glEnable(GL_BLEND);

glEnable(GL_DEPTH_TEST);

glEnableClientState(GL_VERTEX_ARRAY); //3

if(m_UseNormals)

glEnableClientState(GL_NORMAL_ARRAY);

glVertexPointer(3,GL_FLOAT,0,(GLvoid*)(char*)0); //4

glNormalPointer(GL_FLOAT,0,(const GLvoid*)(char*)(0+m_TotalXYZBytes));

glTexCoordPointer(2,GL_FLOAT,0,

(const GLvoid*)((char*)(m_TotalXYZBytes+m_TotalNormalBytes)));

if(m_UseTexture)

{

if(m_TexCoordsData!=nil)

{

glEnable(GL_TEXTURE_2D);

glEnableClientState(GL_TEXTURE_COORD_ARRAY);

if(m_TextureID!=0)

glBindTexture(GL_TEXTURE_2D, m_TextureID);

}

}

else

glDisableClientState(GL_TEXTURE_COORD_ARRAY);

//5

glDrawArrays(GL_TRIANGLE_STRIP, 0, (m_Slices+1)*2*(m_Stacks-1)+2);

glDisable(GL_BLEND);

glDisable(GL_TEXTURE_2D);

return true;

}