/*

     File: PaintingView.m

 Abstract: The class responsible for the finger painting. The class wraps the 

 CAEAGLLayer from CoreAnimation into a convenient UIView subclass. The view 

 content is basically an EAGL surface you render your OpenGL scene into.

  Version: 1.13

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

 Inc. ("Apple") in consideration of your agreement to the following

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 redistribute this Apple software.

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 "Apple Software"), to use, reproduce, modify and redistribute the Apple

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 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

 expressly stated in this notice, no other rights or licenses, express or

 implied, are granted by Apple herein, including but not limited to any

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 works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

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 Copyright (C) 2014 Apple Inc. All Rights Reserved.

*/

#import <QuartzCore/QuartzCore.h>

#import <OpenGLES/EAGLDrawable.h>

#import <GLKit/GLKit.h>

#import "PaintingView.h"

#import "shaderUtil.h"

#import "fileUtil.h"

#import "debug.h"

//CONSTANTS:

#define kBrushOpacity       (1.0 / 3.0)

#define kBrushPixelStep     3

#define kBrushScale         2

// Shaders

enum {

    PROGRAM_POINT,

    NUM_PROGRAMS

};

enum {

    UNIFORM_MVP,

    UNIFORM_POINT_SIZE,

    UNIFORM_VERTEX_COLOR,

    UNIFORM_TEXTURE,

    NUM_UNIFORMS

};

enum {

    ATTRIB_VERTEX,

    NUM_ATTRIBS

};

typedef struct {

    char *vert, *frag;

    GLint uniform[NUM_UNIFORMS];

    GLuint id;

} programInfo_t;

programInfo_t program[NUM_PROGRAMS] = {

    { "point.vsh",   "point.fsh" },     // PROGRAM_POINT

};

// Texture

typedef struct {

    GLuint id;

    GLsizei width, height;

} textureInfo_t;

@interface PaintingView()

{

    // The pixel dimensions of the backbuffer

    GLint backingWidth;

    GLint backingHeight;

    EAGLContext *context;

    // OpenGL names for the renderbuffer and framebuffers used to render to this view

    GLuint viewRenderbuffer, viewFramebuffer;

    // OpenGL name for the depth buffer that is attached to viewFramebuffer, if it exists (0 if it does not exist)

    GLuint depthRenderbuffer;

    textureInfo_t brushTexture;     // brush texture

    GLfloat brushColor[4];          // brush color

    Boolean firstTouch;

    Boolean needsErase;

    // Shader objects

    GLuint vertexShader;

    GLuint fragmentShader;

    GLuint shaderProgram;

    // Buffer Objects

    GLuint vboId;

    BOOL initialized;

}

@end

@implementation PaintingView

@synthesize  location;

@synthesize  previousLocation;

// Implement this to override the default layer class (which is [CALayer class]).

// We do this so that our view will be backed by a layer that is capable of OpenGL ES rendering.

+ (Class)layerClass

{

    return [CAEAGLLayer class];

}

// The GL view is stored in the nib file. When it's unarchived it's sent -initWithCoder:

- (id)initWithCoder:(NSCoder*)coder {

    if ((self = [super initWithCoder:coder])) {

        CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;

        eaglLayer.opaque = YES;

        // In this application, we want to retain the EAGLDrawable contents after a call to presentRenderbuffer.

        eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

                                        [NSNumber numberWithBool:YES], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];

        context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];

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

            return nil;

        }

        // Set the view's scale factor as you wish

        self.contentScaleFactor = [[UIScreen mainScreen] scale];

        // Make sure to start with a cleared buffer

        needsErase = YES;

    }

    return self;

}

// If our view is resized, we'll be asked to layout subviews.

// This is the perfect opportunity to also update the framebuffer so that it is

// the same size as our display area.

-(void)layoutSubviews

{

    [EAGLContext setCurrentContext:context];

    if (!initialized) {

        initialized = [self initGL];

    }

    else {

        [self resizeFromLayer:(CAEAGLLayer*)self.layer];

    }

    // Clear the framebuffer the first time it is allocated

    if (needsErase) {

        [self erase];

        needsErase = NO;

    }

}

- (void)setupShaders

{

    for (int i = 0; i < NUM_PROGRAMS; i++)

    {

        char *vsrc = readFile(pathForResource(program[i].vert));

        char *fsrc = readFile(pathForResource(program[i].frag));

        GLsizei attribCt = 0;

        GLchar *attribUsed[NUM_ATTRIBS];

        GLint attrib[NUM_ATTRIBS];

        GLchar *attribName[NUM_ATTRIBS] = {

            "inVertex",

        };

        const GLchar *uniformName[NUM_UNIFORMS] = {

            "MVP", "pointSize", "vertexColor", "texture",

        };

        // auto-assign known attribs

        for (int j = 0; j < NUM_ATTRIBS; j++)

        {

            if (strstr(vsrc, attribName[j]))

            {

                attrib[attribCt] = j;

                attribUsed[attribCt++] = attribName[j];

            }

        }

        glueCreateProgram(vsrc, fsrc,

                          attribCt, (const GLchar **)&attribUsed[0], attrib,

                          NUM_UNIFORMS, &uniformName[0], program[i].uniform,

                          &program[i].id);

        free(vsrc);

        free(fsrc);

        // Set constant/initalize uniforms

        if (i == PROGRAM_POINT)

        {

            glUseProgram(program[PROGRAM_POINT].id);

            // the brush texture will be bound to texture unit 0

            glUniform1i(program[PROGRAM_POINT].uniform[UNIFORM_TEXTURE], 0);

            // viewing matrices

            GLKMatrix4 projectionMatrix = GLKMatrix4MakeOrtho(0, backingWidth, 0, backingHeight, -1, 1);

            GLKMatrix4 modelViewMatrix = GLKMatrix4Identity; // this sample uses a constant identity modelView matrix

            GLKMatrix4 MVPMatrix = GLKMatrix4Multiply(projectionMatrix, modelViewMatrix);

            glUniformMatrix4fv(program[PROGRAM_POINT].uniform[UNIFORM_MVP], 1, GL_FALSE, MVPMatrix.m);

            // point size

            glUniform1f(program[PROGRAM_POINT].uniform[UNIFORM_POINT_SIZE], brushTexture.width / kBrushScale);

            // initialize brush color

            glUniform4fv(program[PROGRAM_POINT].uniform[UNIFORM_VERTEX_COLOR], 1, brushColor);

        }

    }

    glError();

}

// Create a texture from an image

- (textureInfo_t)textureFromName:(NSString *)name

{

    CGImageRef      brushImage;

    CGContextRef    brushContext;

    GLubyte         *brushData;

    size_t          width, height;

    GLuint          texId;

    textureInfo_t   texture;

    // First create a UIImage object from the data in a image file, and then extract the Core Graphics image

    brushImage = [UIImage imageNamed:name].CGImage;

    // Get the width and height of the image

    width = CGImageGetWidth(brushImage);

    height = CGImageGetHeight(brushImage);

    // Make sure the image exists

    if(brushImage) {

        // Allocate  memory needed for the bitmap context

        brushData = (GLubyte *) calloc(width * height * 4, sizeof(GLubyte));

        // Use  the bitmatp creation function provided by the Core Graphics framework.

        brushContext = CGBitmapContextCreate(brushData, width, height, 8, width * 4, CGImageGetColorSpace(brushImage), kCGImageAlphaPremultipliedLast);

        // After you create the context, you can draw the  image to the context.

        CGContextDrawImage(brushContext, CGRectMake(0.0, 0.0, (CGFloat)width, (CGFloat)height), brushImage);

        // You don't need the context at this point, so you need to release it to avoid memory leaks.

        CGContextRelease(brushContext);

        // Use OpenGL ES to generate a name for the texture.

        glGenTextures(1, &texId);

        // Bind the texture name.

        glBindTexture(GL_TEXTURE_2D, texId);

        // Set the texture parameters to use a minifying filter and a linear filer (weighted average)

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        // Specify a 2D texture image, providing the a pointer to the image data in memory

        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (int)width, (int)height, 0, GL_RGBA, GL_UNSIGNED_BYTE, brushData);

        // Release  the image data; it's no longer needed

        free(brushData);

        texture.id = texId;

        texture.width = (int)width;

        texture.height = (int)height;

    }

    return texture;

}

- (BOOL)initGL

{

    // Generate IDs for a framebuffer object and a color renderbuffer

    glGenFramebuffers(1, &viewFramebuffer);

    glGenRenderbuffers(1, &viewRenderbuffer);

    glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

    glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);

    // This call associates the storage for the current render buffer with the EAGLDrawable (our CAEAGLLayer)

    // allowing us to draw into a buffer that will later be rendered to screen wherever the layer is (which corresponds with our view).

    [context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(id<EAGLDrawable>)self.layer];

    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer);

    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);

    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);

    // For this sample, we do not need a depth buffer. If you do, this is how you can create one and attach it to the framebuffer:

//    glGenRenderbuffers(1, &depthRenderbuffer);

//    glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);

//    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, backingWidth, backingHeight);

//    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);

    if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)

    {

        NSLog(@"failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));

        return NO;

    }

    // Setup the view port in Pixels

    glViewport(0, 0, backingWidth, backingHeight);

    // Create a Vertex Buffer Object to hold our data

    glGenBuffers(1, &vboId);

    // Load the brush texture

    brushTexture = [self textureFromName:@"Particle.png"];

    // Load shaders

    [self setupShaders];

    // Enable blending and set a blending function appropriate for premultiplied alpha pixel data

    glEnable(GL_BLEND);

    glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

    // Playback recorded path, which is "Shake Me"

    NSMutableArray* recordedPaths = [NSMutableArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Recording" ofType:@"data"]];

    if([recordedPaths count])

        [self performSelector:@selector(playback:) withObject:recordedPaths afterDelay:0.2];

    return YES;

}

- (BOOL)resizeFromLayer:(CAEAGLLayer *)layer

{

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

    glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);

    [context renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer];

    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);

    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);

    // For this sample, we do not need a depth buffer. If you do, this is how you can allocate depth buffer backing:

//    glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);

//    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, backingWidth, backingHeight);

//    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);

    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)

    {

        NSLog(@"Failed to make complete framebuffer objectz %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));

        return NO;

    }

    // Update projection matrix

    GLKMatrix4 projectionMatrix = GLKMatrix4MakeOrtho(0, backingWidth, 0, backingHeight, -1, 1);

    GLKMatrix4 modelViewMatrix = GLKMatrix4Identity; // this sample uses a constant identity modelView matrix

    GLKMatrix4 MVPMatrix = GLKMatrix4Multiply(projectionMatrix, modelViewMatrix);

    glUseProgram(program[PROGRAM_POINT].id);

    glUniformMatrix4fv(program[PROGRAM_POINT].uniform[UNIFORM_MVP], 1, GL_FALSE, MVPMatrix.m);

    // Update viewport

    glViewport(0, 0, backingWidth, backingHeight);

    return YES;

}

// Releases resources when they are not longer needed.

- (void)dealloc

{

    // Destroy framebuffers and renderbuffers

    if (viewFramebuffer) {

        glDeleteFramebuffers(1, &viewFramebuffer);

        viewFramebuffer = 0;

    }

    if (viewRenderbuffer) {

        glDeleteRenderbuffers(1, &viewRenderbuffer);

        viewRenderbuffer = 0;

    }

    if (depthRenderbuffer)

    {

        glDeleteRenderbuffers(1, &depthRenderbuffer);

        depthRenderbuffer = 0;

    }

    // texture

    if (brushTexture.id) {

        glDeleteTextures(1, &brushTexture.id);

        brushTexture.id = 0;

    }

    // vbo

    if (vboId) {

        glDeleteBuffers(1, &vboId);

        vboId = 0;

    }

    // tear down context

    if ([EAGLContext currentContext] == context)

        [EAGLContext setCurrentContext:nil];

}

// Erases the screen

- (void)erase

{

    [EAGLContext setCurrentContext:context];

    // Clear the buffer

    glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

    glClearColor(0.0, 0.0, 0.0, 0.0);

    glClear(GL_COLOR_BUFFER_BIT);

    // Display the buffer

    glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);

    [context presentRenderbuffer:GL_RENDERBUFFER];

}

// Drawings a line onscreen based on where the user touches

- (void)renderLineFromPoint:(CGPoint)start toPoint:(CGPoint)end

{

    static GLfloat*     vertexBuffer = NULL;

    static NSUInteger   vertexMax = 64;

    NSUInteger          vertexCount = 0,

                        count,

                        i;

    [EAGLContext setCurrentContext:context];

    glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

    // Convert locations from Points to Pixels

    CGFloat scale = self.contentScaleFactor;

    start.x *= scale;

    start.y *= scale;

    end.x *= scale;

    end.y *= scale;

    // Allocate vertex array buffer

    if(vertexBuffer == NULL)

        vertexBuffer = malloc(vertexMax * 2 * sizeof(GLfloat));

    // Add points to the buffer so there are drawing points every X pixels

    count = MAX(ceilf(sqrtf((end.x - start.x) * (end.x - start.x) + (end.y - start.y) * (end.y - start.y)) / kBrushPixelStep), 1);

    for(i = 0; i < count; ++i) {

        if(vertexCount == vertexMax) {

            vertexMax = 2 * vertexMax;

            vertexBuffer = realloc(vertexBuffer, vertexMax * 2 * sizeof(GLfloat));

        }

        vertexBuffer[2 * vertexCount + 0] = start.x + (end.x - start.x) * ((GLfloat)i / (GLfloat)count);

        vertexBuffer[2 * vertexCount + 1] = start.y + (end.y - start.y) * ((GLfloat)i / (GLfloat)count);

        vertexCount += 1;

    }

    // Load data to the Vertex Buffer Object

    glBindBuffer(GL_ARRAY_BUFFER, vboId);

    glBufferData(GL_ARRAY_BUFFER, vertexCount*2*sizeof(GLfloat), vertexBuffer, GL_DYNAMIC_DRAW);

    glEnableVertexAttribArray(ATTRIB_VERTEX);

    glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, GL_FALSE, 0, 0);

    // Draw

    glUseProgram(program[PROGRAM_POINT].id);

    glDrawArrays(GL_POINTS, 0, (int)vertexCount);

    // Display the buffer

    glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);

    [context presentRenderbuffer:GL_RENDERBUFFER];

}

// Reads previously recorded points and draws them onscreen. This is the Shake Me message that appears when the application launches.

- (void)playback:(NSMutableArray*)recordedPaths

{

    // NOTE: Recording.data is stored with 32-bit floats

    // To make it work on both 32-bit and 64-bit devices, we make sure we read back 32 bits each time.

    Float32 x[1], y[1];

    CGPoint point1, point2;

    NSData*             data = [recordedPaths objectAtIndex:0];

    NSUInteger          count = [data length] / (sizeof(Float32)*2), // each point contains 64 bits (32-bit x and 32-bit y)

                        i;

    // Render the current path

    for(i = 0; i < count - 1; i++) {

        [data getBytes:&x range:NSMakeRange(8*i, sizeof(Float32))]; // read 32 bits each time

        [data getBytes:&y range:NSMakeRange(8*i+sizeof(Float32), sizeof(Float32))];

        point1 = CGPointMake(x[0], y[0]);

        [data getBytes:&x range:NSMakeRange(8*(i+1), sizeof(Float32))];

        [data getBytes:&y range:NSMakeRange(8*(i+1)+sizeof(Float32), sizeof(Float32))];

        point2 = CGPointMake(x[0], y[0]);

        [self renderLineFromPoint:point1 toPoint:point2];

    }

    // Render the next path after a short delay 

    [recordedPaths removeObjectAtIndex:0];

    if([recordedPaths count])

        [self performSelector:@selector(playback:) withObject:recordedPaths afterDelay:0.01];

}

// Handles the start of a touch

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

{   

    CGRect              bounds = [self bounds];

    UITouch*            touch = [[event touchesForView:self] anyObject];

    firstTouch = YES;

    // Convert touch point from UIView referential to OpenGL one (upside-down flip)

    location = [touch locationInView:self];

    location.y = bounds.size.height - location.y;

}

// Handles the continuation of a touch.

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event

{   

    CGRect              bounds = [self bounds];

    UITouch*            touch = [[event touchesForView:self] anyObject];

    // Convert touch point from UIView referential to OpenGL one (upside-down flip)

    if (firstTouch) {

        firstTouch = NO;

        previousLocation = [touch previousLocationInView:self];

        previousLocation.y = bounds.size.height - previousLocation.y;

    } else {

        location = [touch locationInView:self];

        location.y = bounds.size.height - location.y;

        previousLocation = [touch previousLocationInView:self];

        previousLocation.y = bounds.size.height - previousLocation.y;

    }

    // Render the stroke

    [self renderLineFromPoint:previousLocation toPoint:location];

}

// Handles the end of a touch event when the touch is a tap.

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

{

    CGRect              bounds = [self bounds];

    UITouch*            touch = [[event touchesForView:self] anyObject];

    if (firstTouch) {

        firstTouch = NO;

        previousLocation = [touch previousLocationInView:self];

        previousLocation.y = bounds.size.height - previousLocation.y;

        [self renderLineFromPoint:previousLocation toPoint:location];

    }

}

// Handles the end of a touch event.

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event

{

    // If appropriate, add code necessary to save the state of the application.

    // This application is not saving state.

}

- (void)setBrushColorWithRed:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue

{

    // Update the brush color

    brushColor[0] = red * kBrushOpacity;

    brushColor[1] = green * kBrushOpacity;

    brushColor[2] = blue * kBrushOpacity;

    brushColor[3] = kBrushOpacity;

    if (initialized) {

        glUseProgram(program[PROGRAM_POINT].id);

        glUniform4fv(program[PROGRAM_POINT].uniform[UNIFORM_VERTEX_COLOR], 1, brushColor);

    }

}

- (BOOL)canBecomeFirstResponder {

    return YES;

}

@end