IOS8新技术metal入门
这里是参考http://metalbyexample.com/up-and-running-1/，我这里只是大概初步引导，还是看原文过瘾。metal技术需要新机调试，移动设备需要是a7 a8处理器，比如iPhone6，iPhone5c，ipad air2不能用模拟器来调试。
1、首先创建了一个简单的singleView项目。并添加框架，metal uikit foundation quartzcore。
2、添加类MetalView，继承 UIView，在类中声明属性
@property (nonatomic,strong) id<MTLDevice> device;
@property (nonatomic,weak) CAMetalLayer *metalLayer;
在类实现中，添加方法
+ (id)layerClass
{
return [CAMetalLayerclass];
}
- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
if ((self = [superinitWithCoder:aDecoder]))
{
_metalLayer = (CAMetalLayer *)[selflayer];
_device =MTLCreateSystemDefaultDevice();
_metalLayer.device =_device;
_metalLayer.pixelFormat =MTLPixelFormatBGRA8Unorm;
}
returnself;
}
- (void)didMoveToWindow
{
[selfredraw];
}
- (void)redraw
{
id<CAMetalDrawable> drawable = [self.metalLayernextDrawable];
id<MTLTexture> texture = drawable.texture;
MTLRenderPassDescriptor *passDescriptor = [MTLRenderPassDescriptorrenderPassDescriptor];
passDescriptor.colorAttachments[0].texture = texture;
passDescriptor.colorAttachments[0].loadAction =MTLLoadActionClear;
passDescriptor.colorAttachments[0].storeAction =MTLStoreActionStore;
passDescriptor.colorAttachments[0].clearColor =MTLClearColorMake(1.0,0.0, 0.0,1.0);
id<MTLCommandQueue> commandQueue = [self.devicenewCommandQueue];
id<MTLCommandBuffer> commandBuffer = [commandQueuecommandBuffer];
id <MTLRenderCommandEncoder> commandEncoder = [commandBufferrenderCommandEncoderWithDescriptor:passDescriptor];
[commandEncoder endEncoding];
[commandBuffer presentDrawable:drawable];
[commandBuffer commit];
}
大概意思是，在cpu上创建好绘制的各种参数，然后传输到gpu，由gpu解析执行需要绘制的命令参数。有opengl或gpu编程经验会很好理解的。
3、把storyboard的里的view类属性选成MetalView类型，然后就commad+r吧，执行看看，红色背景图。
更改passDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(1.0, 0.0, 0.0, 1.0);这里的颜色。
源代码可以到原文中下载。我这也有http://download.csdn.net/detail/huyisu/8409671