From 57fecdc09e1659db9ec17e9856448e7e77d21ffb Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 9 Aug 2020 18:41:15 -0400
Subject: [PATCH] Ties everything together in an attempt to display RGB scans.

I'm actually just getting a mess of pixels, but it's something!
---
 .../Clock Signal/ScanTarget/CSScanTarget.mm   | 33 ++++++++++---------
 .../Clock Signal/ScanTarget/ScanTarget.metal  | 12 +++++--
 2 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm b/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm
index 9d1097390..8d8b2bc7b 100644
--- a/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm	
+++ b/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm	
@@ -40,7 +40,7 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
 
 	id<MTLFunction> _vertexShader;
 	id<MTLFunction> _fragmentShader;
-	id<MTLRenderPipelineState> _gouraudPipeline;
+	id<MTLRenderPipelineState> _scanPipeline;
 
 	// Buffers.
 	id<MTLBuffer> _uniformsBuffer;
@@ -85,14 +85,6 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
 		_scanTarget.set_write_area(reinterpret_cast<uint8_t *>(_writeAreaBuffer.contents));
 		_scanTarget.set_line_buffer(reinterpret_cast<BufferingScanTarget::Line *>(_linesBuffer.contents), _lineMetadataBuffer, NumBufferedLines);
 		_scanTarget.set_scan_buffer(reinterpret_cast<BufferingScanTarget::Scan *>(_scansBuffer.contents), NumBufferedScans);
-
-		// Generate TEST pipeline.
-		id<MTLLibrary> library = [view.device newDefaultLibrary];
-		MTLRenderPipelineDescriptor *pipelineDescriptor = [[MTLRenderPipelineDescriptor alloc] init];
-		pipelineDescriptor.vertexFunction = [library newFunctionWithName:@"scanVertexMain"];
-		pipelineDescriptor.fragmentFunction = [library newFunctionWithName:@"scanFragmentMain"];
-		pipelineDescriptor.colorAttachments[0].pixelFormat = view.colorPixelFormat;
-		_gouraudPipeline = [view.device newRenderPipelineStateWithDescriptor:pipelineDescriptor error:nil];
 	}
 
 	return self;
@@ -115,11 +107,6 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
  @discussion Called on the delegate when it is asked to render into the view
  */
 - (void)drawInMTKView:(nonnull MTKView *)view {
-	// Generate a command encoder for the view.
-	id <MTLCommandBuffer> commandBuffer = [_commandQueue commandBuffer];
-	MTLRenderPassDescriptor *const descriptor = view.currentRenderPassDescriptor;
-	id <MTLRenderCommandEncoder> encoder = [commandBuffer renderCommandEncoderWithDescriptor:descriptor];
-
 	const Outputs::Display::ScanTarget::Modals *const newModals = _scanTarget.new_modals();
 	if(newModals) {
 		uniforms()->scale[0] = newModals->output_scale.x;
@@ -150,11 +137,25 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
 			offset:0
 			bytesPerRow:BufferingScanTarget::WriteAreaWidth * _bytesPerInputPixel];
 		_totalTextureBytes = BufferingScanTarget::WriteAreaWidth * BufferingScanTarget::WriteAreaHeight * _bytesPerInputPixel;
+
+		// Generate pipeline.
+		id<MTLLibrary> library = [view.device newDefaultLibrary];
+		MTLRenderPipelineDescriptor *pipelineDescriptor = [[MTLRenderPipelineDescriptor alloc] init];
+		pipelineDescriptor.vertexFunction = [library newFunctionWithName:@"scanVertexMain"];
+		pipelineDescriptor.fragmentFunction = [library newFunctionWithName:@"scanFragmentMain"];
+		pipelineDescriptor.colorAttachments[0].pixelFormat = view.colorPixelFormat;
+		_scanPipeline = [view.device newRenderPipelineStateWithDescriptor:pipelineDescriptor error:nil];
 	}
 
-	// Drawing. Just the test triangle, as described above.
-	[encoder setRenderPipelineState:_gouraudPipeline];
+	// Generate a command encoder for the view.
+	id <MTLCommandBuffer> commandBuffer = [_commandQueue commandBuffer];
+	MTLRenderPassDescriptor *const descriptor = view.currentRenderPassDescriptor;
+	id <MTLRenderCommandEncoder> encoder = [commandBuffer renderCommandEncoderWithDescriptor:descriptor];
 
+	// Drawing. Just scans.
+	[encoder setRenderPipelineState:_scanPipeline];
+
+	[encoder setFragmentTexture:_writeAreaTexture atIndex:0];
 	[encoder setVertexBuffer:_scansBuffer offset:0 atIndex:0];
 	[encoder setVertexBuffer:_uniformsBuffer offset:0 atIndex:1];
 
diff --git a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal
index b75921fde..e54400af8 100644
--- a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal	
+++ b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal	
@@ -51,6 +51,7 @@ struct Line {
 // This is an intermediate struct, which is TEMPORARY.
 struct ColouredVertex {
 	float4 position [[position]];
+	float2 textureCoordinates;
 };
 
 
@@ -81,9 +82,16 @@ vertex ColouredVertex scanVertexMain(	constant Uniforms &uniforms [[buffer(1)]],
 		0.0,
 		1.0
 	);
+	output.textureCoordinates = float2(
+		mix(scans[instanceID].endPoints[0].dataOffset, scans[instanceID].endPoints[1].dataOffset, float((vertexID&2) >> 1)),
+		scans[instanceID].dataY);
 	return output;
 }
 
-fragment half4 scanFragmentMain(ColouredVertex vert [[stage_in]]) {
-	return half4(1.0);
+fragment half4 scanFragmentMain(ColouredVertex vert [[stage_in]], texture2d<float> texture [[texture(0)]]) {
+	constexpr sampler s(coord::pixel,
+						address::clamp_to_zero,	// This really makes no difference here; anything Metal will accept will do.
+						filter::nearest);
+
+	return half4(texture.sample(s, vert.textureCoordinates));
 }