iOSの新グラフィックAPI - Metal入門してみる ref: https://qiita.com/edo_m18/items/0fd6971c98c27a125d6e

create-CAMetalLayer

import QuartzCore;

// CAMetalLayerの生成
CAMetalLayer *metalLayer = [CAMetalLayer layer];
metalLayer.device = device;
metalLayer.pixelFormat = MTLPixelFormatBGRA8Unorm;
metalLayer.framebufferOnly = YES;
metalLayer.frame = self.view.layer.frame;
[self.view.layer addSublayer:metalLayer];

Create-Command_queue

id <MTLCommandQueue> commandQueue = [device newCommandQueue];

create-Fragment_shader

fragment half4 basic_fragment() {
    return half4(1.0);
}

create-MTLDevice

// MTLDeivceの生成
id <MTLDevice> device = MTLCreateSystemDefaultDevice();

Create-Render_command_encoder

// Render Command Encoderの生成
id <MTLRenderCommandEncoder> renderEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];

if (renderEncoder) {
    [renderEncoder setRenderPipelineState:self.pipelineState];
    [renderEncoder setVertexBuffer:self.vertexBuffer offset:0 atIndex:0];
    [renderEncoder drawPrimitives:MTLPrimitiveTypeTriangle vertexStart:0 vertexCount:3 instanceCount:1];
    [renderEncoder endEncoding];
}

Create-Render_pipeline

id <MTLRenderPipelineState> pipelineState;

id <MTLLibrary> defaultLibrary   = [device newDefaultLibrary];
id <MTLFunction> fragmentProgram = [defaultLibrary newFunctionWithName:@"basic_fragment"];
id <MTLFunction> vertexProgram   = [defaultLibrary newFunctionWithName:@"basic_vertex"];

MTLRenderPipelineDescriptor *pipelineStateDescriptor = [[MTLRenderPipelineDescriptor alloc] init];
pipelineStateDescriptor.vertexFunction   = vertexProgram;
pipelineStateDescriptor.fragmentFunction = fragmentProgram;
[pipelineStateDescriptor.colorAttachments objectAtIndexedSubscript:0].pixelFormat = MTLPixelFormatBGRA8Unorm;

NSError *pipelineError = nil;
pipelineState = [device newRenderPipelineStateWithDescriptor:pipelineStateDescriptor error:&pipelineError];

if (!pipelineState) {
    NSLog(@"Failed to create pipeline state, error %@", pipelineError);
}

create-Vertex_Buffer

// 頂点情報
CGFloat vertexData[] = {
     0.0,  1.0, 0.0,
    -1.0, -1.0, 0.0,
     1.0, -1.0, 0.0,
};

NSInteger dataSize = sizeof(vertexData);
id <MTLBuffer> vertexBuffer = [device newBufferWithBytes:vertexData length:dataSize options:MTLResourceOptionCPUCacheModeDefault];

create-Vertex_shader

vertex float4 basic_vertex(
    const device packed_float3 *vertex_array [[buffer(0)]],
                           unsigned int vid [[vertex_id]]) {
    return float4(vertex_array[vid], 1.0);
}

file11.m

CADisplayLink *timer = [CADisplayLink displayLinkWithTarget:self selector:@selector(gameloop)];
[timer addToRunLoop:NSRunLoop.mainRunLoop forMode:NSDefaultRunLoopMode];

/////////////////////////////////////////////////////////////////////////////

- (void)gameloop
{
    @autoreleasepool {
        [self render];
    }
}

file12.m

// Render Pass Descriptorの生成。
MTLRenderPassDescriptor *renderPassDescriptor = [[MTLRenderPassDescriptor alloc] init];
renderPassDescriptor.colorAttachments[0].texture     = texture;
renderPassDescriptor.colorAttachments[0].loadAction  = MTLLoadActionClear;
renderPassDescriptor.colorAttachments[0].clearColor  = MTLClearColorMake(0.0, 104.0/255.0, 5.0/255.0, 1.0);
renderPassDescriptor.colorAttachments[0].storeAction = MTLStoreActionStore;

file13.txt

// create a new command queue
_commandQueue = [_device newCommandQueue];

/////////////////////////////////////////////////////////////////////////////

id <MTLCommandBuffer> commandBuffer = [_commandQueue commandBuffer];

file15.m

// 頂点データを定義する
static const float vertexData[] = {
     0.0, -1.0, 0.0,
    -1.0,  1.0, 0.0,
     1.0,  1.0, 0.0
};

file16.m

id <MTLBuffer> buffer = [device newBufferWithBytes:vertexData length:sizeof(vertexData) options:MTLResourceOptionCPUCacheModelDefault];

file17.m

static const float uniformData[] {
    1.0, 1.0, 1.0, 1.0,
};

file18.m

id <MTLBuffer> uniformBuffer = [device newBufferWithLength:sizeof(uniformData) options:MTLResourceOptionCPUCacheModelDefault];

file19.m

void *buf = [uniformBuffer contents];
memcpy(buf, uniformData, sizeof(uniformData));

file20.m

[commandBuffer presentDrawable:view.currentDrawable];
[commandBuffer commit];

file4.txt

// 構造体の宣言
struct VertexIn {
    packed_float3 position;
    packed_float4 color;
};

struct VertexOut {
    float4 position [[position]];
    float4 color;
};

vertex VertexOut vertex_shader_function(const device VertexIn *vertex_array [[buffer(0)]], unsigned int vid [[vertex_id]]) {
    // do something.
}

fragment half4 fragment_shader_function(VertexOut input [[stage_in]]) {
    // do something.
}

file5.txt

vertex float4 vertex_function(const device packed_float3 *vertex_array [[buffer(0)]],
                              const device Uniforms &uniforms     [[buffer(1)]],
                              unsigned int vid [[vertex_id]]) {
    // ...
}

file6.m

id <MTLRenderCommandEncoder> renderEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];

[renderEncoder setVertexBuffer:vertexBuffer offset:0 atIndex:0];

file7.m

CGFloat data[] = {
    1, 2,  3,  4,  5,  6,  7, // 7個でひとつの頂点分の情報になる
    8, 9, 10, 11, 12, 13, 14,
    ...
};