A GLKVC with frag and vertex shaders as files and with the CeedGL lib. Coord space mapped to 0,0...1,1. #glsl #opengl

GLKViewController-with-CeedGL-Boilerplate.m

/*******

*** vertex.glsl ***********

uniform mat4 u_projection_matrix;
attribute vec4 a_position;
//attribute vec4 a_source_color;
varying vec4 v_position;

void main(void)
{
    // We'll map position (0..1) to colour in the frag shader
    v_position = a_position;
    
    // Multiply by our scale correction matrix
    gl_Position = u_projection_matrix * a_position;
}


*** fragment.glsl ***********

varying highp vec4 v_position;

void main(void)
{
    gl_FragColor = vec4(v_position.y,1,1,0);
}


*******/

#import "SPTemperatureGLBackgroundVC.h"
#import "CeedGL.h"

@implementation SPTemperatureGLBackgroundVC
{
    EAGLContext *_context;
    GLProgram *_glProgram;
    GLShader *_glShader;
    GLDrawCommand *_glRenderer;
}


/////////////////////////////////////////////////////////////////////////
#pragma mark - Life Cycle
/////////////////////////////////////////////////////////////////////////


- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.delegate = self;
    
    // Setup the GL
    GLKView *view = (GLKView *)self.view;
    _context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
    
#warning TODO: Check for success....
    
    view.context = _context;
    view.drawableMultisample = GLKViewDrawableMultisample4X;
    view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
    
    [self _setupGL];
}

//---------------------------------------------------------------------

- (void)viewWillAppear:(BOOL)animated
{
    // Be sure to update the current context when the screen shows
    [EAGLContext setCurrentContext:_context];
}

//---------------------------------------------------------------------

- (void)viewWillDisappear:(BOOL)animated
{
    // Clean up context to prevent conflict with others.
    // Only unset if someone else hasn't already...
    if ([EAGLContext currentContext] == _context) {
        [EAGLContext setCurrentContext:nil];
    }
}

//---------------------------------------------------------------------


- (void)viewDidUnload
{
    [super viewDidUnload];
    
    // Break all the GL down
    [self _tearDownGL];
    if ([EAGLContext currentContext] == _context) {
        [EAGLContext setCurrentContext:nil];
    }
  _context = nil;
}


//---------------------------------------------------------------------


- (void)_setupGL
{
    
    /////////////////////////////////////////
    // SHADERS, LOAD, COMPILE, ATTACH
    /////////////////////////////////////////
    NSString *filePath;

    [EAGLContext setCurrentContext:_context];
    _glProgram = [GLProgram program];
    filePath = [[NSBundle mainBundle] pathForResource:@"vertex" ofType:@"glsl"];
    NSString *vertexSrc = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
    filePath = [[NSBundle mainBundle] pathForResource:@"fragment" ofType:@"glsl"];
    NSString *fragmentSrc = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
    
    NSError *error = nil;
    GLShader *vshader = [GLShader vertexShader], *fshader = [GLShader fragmentShader];
    [vshader setSource:vertexSrc];
    if(![vshader compile:&error]) { DDLogError(@"Vertex shader compilation error: %@", error); }
    
    [fshader setSource:fragmentSrc];
    if(![fshader compile:&error]) { DDLogError(@"Fragment shader compilation error: %@", error); }
    
    [_glProgram attachShader:vshader];
    [_glProgram attachShader:fshader];
    [_glProgram bindAttributeLocation:0 forName:@"a_position"];
    
    if(![_glProgram link:&error])  { NSLog(@"Could not link program error: %@", error); }
    
    
    /////////////////////////////////////////
    // DRAWING DATA & BINDINGS
    /////////////////////////////////////////

    // Create the drawing renderer
    _glRenderer = [GLDrawCommand drawCommand];
    _glRenderer.program = _glProgram;
    _glRenderer.mode = GL_TRIANGLES;
    _glRenderer.firstElement = 0;
    _glRenderer.elementCount = 6;
    
    
    GLBuffer *attr = [GLBuffer buffer];
    GLfloat pos[] = {0,0,  1,0,  0,1,  1,1, 1,0, 0,1};
    [attr loadData:pos size:sizeof(pos) usage:GL_STATIC_DRAW target:GL_ARRAY_BUFFER];
    [_glRenderer setAttributeBuffer:attr size:2 type:GL_FLOAT normalized:GL_FALSE stride:0 offset:0 forName:@"a_position"];
    
//    [_glRenderer setAttribute:[GLValue vectorWithFloats:1 :1 :0 :1] forName:@"a_source_color"];
    
    // Correct our view coords to be  0,0 -> 1,1 for easier shader color mapping
    GLKMatrix4 projection = GLKMatrix4MakeScale(2, 2, 2);
    projection = GLKMatrix4Translate(projection, -0.5, -0.5, 0);
    [_glRenderer setUniform:[GLValue matrixWithFloats:projection.m size:4] forName:@"u_projection_matrix"];

    [EAGLContext setCurrentContext:nil];
}

//---------------------------------------------------------------------


- (void)_tearDownGL
{
    
}



/////////////////////////////////////////////////////////////////////////
#pragma mark - Delegates
/////////////////////////////////////////////////////////////////////////

- (void)glkViewControllerUpdate:(GLKViewController *)controller
{
    
}

//---------------------------------------------------------------------

- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
    glClearColor(0, 0, 0.3, 1.0);
    glClear(GL_COLOR_BUFFER_BIT); // | GL_DEPTH_BUFFER_BIT);

    [_glRenderer draw];
}



@end