Pro OpenGL ES for iOS

78 CHAPTER 3: Building a 3D World^

The first thing to do is create a new project derived from the bouncy square example.

But instead of building up all the geometry in drawInRect(), you can create a new object

called Planet and initialize the data, as in Listing 3-6a for the header and Listing 3-6b for

the init method.

Listing 3-6a. Building our 3D Planet

#import <Foundation/Foundation.h>

#import <OpenGLES/ES1/gl.h>

@interface Planet : NSObject

{

@private

GLfloat *m_VertexData;

GLubyte *m_ColorData;

GLint m_Stacks, m_Slices;

GLfloat m_Scale;

GLfloat m_Squash;

}

• (bool)execute;


• (id) init:(GLint)stacks slices:(GLint)slices radius:(GLfloat)radius squash:(GLfloat)
  squash;

@end

Listing 3-6b. 3D Sphere generator

• (id) init:(GLint)stacks slices:(GLint)slices radius:(GLfloat)radius squash:(GLfloat)
  squash
  {
  unsigned int colorIncrment=0; //1
  unsigned int blue=0;
  unsigned int red=255;

m_Scale=radius;

m_Squash=squash;

colorIncrment=255/stacks; //2

if ((self = [super init]))

{

m_Stacks = stacks;

m_Slices = slices;

m_VertexData = nil;