/*

 File: ES1Renderer.m

 Abstract: The ES1Renderer class creates an OpenGL ES 1.1 context and draws 

 using OpenGL ES 1.1 functions.

 Version: 1.0

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*/

#import "ES1Renderer.h"

@implementation ES1Renderer

// Create an ES 1.1 context

- (id <ESRenderer>) init

{

    if (self = [super init])

    {

        context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];

        if (!context || ![EAGLContext setCurrentContext:context])

        {

            [self release];

            return nil;

        }

        // Create default framebuffer object. The backing will be allocated for the current layer in -resizeFromLayer

        glGenFramebuffersOES(1, &defaultFramebuffer);

        glGenRenderbuffersOES(1, &colorRenderbuffer);

        glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer);

        glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);

        glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, colorRenderbuffer);

    }

    return self;

}

- (void) render {

    // Replace the implementation of this method to do your own custom drawing

    const GLfloat squareVertices[] = {

        -0.5f, -0.5f,

        0.5f,  -0.5f,

        -0.5f,  0.5f,

        0.5f,   0.5f,

    };

    const GLubyte squareColors[] = {

        255, 255,   0, 255,

        0,   255, 255, 255,

        0,     0,   0,   0,

        255,   0, 255, 255,

    };

    [EAGLContext setCurrentContext:context];

    glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer);

    glViewport(0, 0, backingWidth, backingHeight);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f);

    glMatrixMode(GL_MODELVIEW);

    glRotatef(3.0f, 0.0f, 0.0f, 1.0f);

    glClearColor(0.5f, 0.5f, 0.5f, 1.0f);

    glClear(GL_COLOR_BUFFER_BIT);

    glVertexPointer(2, GL_FLOAT, 0, squareVertices);

    glEnableClientState(GL_VERTEX_ARRAY);

    glColorPointer(4, GL_UNSIGNED_BYTE, 0, squareColors);

    glEnableClientState(GL_COLOR_ARRAY);

    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

    glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);

    [context presentRenderbuffer:GL_RENDERBUFFER_OES];

}

- (BOOL) resizeFromLayer:(CAEAGLLayer *)layer

{   

    // Allocate color buffer backing based on the current layer size

    glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);

    [context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:layer];

    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);

    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);

    if (glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES) != GL_FRAMEBUFFER_COMPLETE_OES)

    {

        NSLog(@"Failed to make complete framebuffer object %x", glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES));

        return NO;

    }

    return YES;

}

- (void) dealloc

{

    // Tear down GL

    if (defaultFramebuffer)

    {

        glDeleteFramebuffersOES(1, &defaultFramebuffer);

        defaultFramebuffer = 0;

    }

    if (colorRenderbuffer)

    {

        glDeleteRenderbuffersOES(1, &colorRenderbuffer);

        colorRenderbuffer = 0;

    }

    // Tear down context

    if ([EAGLContext currentContext] == context)

        [EAGLContext setCurrentContext:nil];

    [context release];

    context = nil;

    [super dealloc];

}

@end