/*

 Copyright (C) 2015 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Texture Loading classes for Metal. Includes examples of how to load a 2D, and Cubemap textures.

 */

#import "AAPLTexture.h"

@interface AAPLTexture ()

@property (readwrite) id <MTLTexture> texture;

@property (readwrite) uint32_t width;

@property (readwrite) uint32_t height;

@property (readwrite) uint32_t pixelFormat;

@property (readwrite) uint32_t target;

@property (readwrite) BOOL hasAlpha;

@end

@implementation AAPLTexture

- (instancetype)initWithResourceName:(NSString *)name extension:(NSString *)ext

{

    NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:ext];

    if (!path)

        return nil;

    self = [super init];

    if (self) {

        _pathToTextureFile = path;

        _width = _height = 0;

        _depth = 1;

    }

    return self;

}

- (BOOL)loadIntoTextureWithDevice:(id <MTLDevice>)device

{

    // to be implemented by subclasses

    assert(0);

}

@end

@implementation AAPLTexture2D

// assumes png file

- (BOOL)loadIntoTextureWithDevice:(id <MTLDevice>)device

{

    UIImage *image = [UIImage imageWithContentsOfFile:self.pathToTextureFile];

    if (!image)

        return NO;

    self.width = (uint32_t)CGImageGetWidth(image.CGImage);

    self.height = (uint32_t)CGImageGetHeight(image.CGImage);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef context = CGBitmapContextCreate( NULL, self.width, self.height, 8, 4 * self.width, colorSpace, (CGBitmapInfo)kCGImageAlphaPremultipliedLast );

    CGContextDrawImage( context, CGRectMake( 0, 0, self.width, self.height ), image.CGImage );

    MTLTextureDescriptor *texDesc = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm

                                                                                     width:self.width

                                                                                    height:self.height

                                                                                 mipmapped:NO];

    self.target = texDesc.textureType;

    self.texture = [device newTextureWithDescriptor:texDesc];

    if (!self.texture)

        return NO;

    [self.texture replaceRegion:MTLRegionMake2D(0, 0, self.width, self.height)

                    mipmapLevel:0

                      withBytes:CGBitmapContextGetData(context)

                    bytesPerRow:4 * self.width];

    CGColorSpaceRelease( colorSpace );

    CGContextRelease(context);

    return YES;

}

@end

@implementation AAPLTextureCubeMap

// assumes png file

- (BOOL)loadIntoTextureWithDevice:(id <MTLDevice>)device

{

    UIImage *image = [UIImage imageWithContentsOfFile:self.pathToTextureFile];

    if (!image)

        return NO;

    self.width = (uint32_t)CGImageGetWidth(image.CGImage);

    self.height = (uint32_t)CGImageGetHeight(image.CGImage);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef context = CGBitmapContextCreate( NULL, self.width, self.height, 8, 4 * self.width, colorSpace, (CGBitmapInfo)kCGImageAlphaPremultipliedLast );

    CGContextDrawImage( context, CGRectMake( 0, 0, self.width, self.height ), image.CGImage );

    unsigned Npixels = self.width * self.width;

    MTLTextureDescriptor *texDesc = [MTLTextureDescriptor textureCubeDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm size:self.width mipmapped:NO];

    self.target = texDesc.textureType;

    self.texture = [device newTextureWithDescriptor:texDesc];

    if (!self.texture)

        return NO;

    void *imageData = CGBitmapContextGetData(context);

    for (int i = 0; i < 6; i++)

    {

        [self.texture replaceRegion:MTLRegionMake2D(0, 0, self.width, self.width)

                        mipmapLevel:0

                              slice:i

                          withBytes:imageData + (i * Npixels * 4)

                        bytesPerRow:4 * self.width

                      bytesPerImage:Npixels * 4];

    }

    CGColorSpaceRelease( colorSpace );

    CGContextRelease(context);

    return YES;

}

@end