From 5c926eeceb7cde6a33e82610a7bdcbdabaf13944 Mon Sep 17 00:00:00 2001
From: David Ludwig <dludwig@pobox.com>
Date: Sat, 9 Feb 2013 20:26:39 -0500
Subject: [PATCH] WinRT: made sure the device orientation transform gets
 applied (by the D3D 11.1 renderer) when drawing

---
 src/render/direct3d11/SDL_render_d3d11.cpp   | 45 ++++++++++++++++----
 src/render/direct3d11/SDL_render_d3d11_cpp.h |  9 ++++
 src/video/windowsrt/SimpleVertexShader.hlsl  | 14 +++++-
 3 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/src/render/direct3d11/SDL_render_d3d11.cpp b/src/render/direct3d11/SDL_render_d3d11.cpp
index 0da2c7697..9712a5d1e 100644
--- a/src/render/direct3d11/SDL_render_d3d11.cpp
+++ b/src/render/direct3d11/SDL_render_d3d11.cpp
@@ -339,6 +339,20 @@ D3D11_CreateDeviceResources(SDL_Renderer * renderer)
         return result;
     }
 
+    //
+    // Setup space to hold vertex shader constants:
+    //
+    CD3D11_BUFFER_DESC constantBufferDesc(sizeof(SDL_VertexShaderConstants), D3D11_BIND_CONSTANT_BUFFER);
+    result = data->d3dDevice->CreateBuffer(
+		&constantBufferDesc,
+		nullptr,
+        &data->vertexShaderConstants
+		);
+    if (FAILED(result)) {
+        WIN_SetErrorFromHRESULT(__FUNCTION__, result);
+        return result;
+    }
+
     //
     // Create a vertex buffer:
     //
@@ -553,7 +567,7 @@ D3D11_CreateWindowSizeDependentResources(SDL_Renderer * renderer)
     {
         case DisplayOrientations::Landscape:
             rotation = DXGI_MODE_ROTATION_IDENTITY;
-            data->orientationTransform3D = XMFLOAT4X4( // 0-degree Z-rotation
+            data->vertexShaderConstantsData.projection = XMFLOAT4X4( // 0-degree Z-rotation
                 1.0f, 0.0f, 0.0f, 0.0f,
                 0.0f, 1.0f, 0.0f, 0.0f,
                 0.0f, 0.0f, 1.0f, 0.0f,
@@ -563,9 +577,9 @@ D3D11_CreateWindowSizeDependentResources(SDL_Renderer * renderer)
 
         case DisplayOrientations::Portrait:
             rotation = DXGI_MODE_ROTATION_ROTATE270;
-            data->orientationTransform3D = XMFLOAT4X4( // 90-degree Z-rotation
-                0.0f, 1.0f, 0.0f, 0.0f,
-                -1.0f, 0.0f, 0.0f, 0.0f,
+            data->vertexShaderConstantsData.projection = XMFLOAT4X4( // 270-degree Z-rotation
+                0.0f, -1.0f, 0.0f, 0.0f,
+                1.0f, 0.0f, 0.0f, 0.0f,
                 0.0f, 0.0f, 1.0f, 0.0f,
                 0.0f, 0.0f, 0.0f, 1.0f
                 );
@@ -573,7 +587,7 @@ D3D11_CreateWindowSizeDependentResources(SDL_Renderer * renderer)
 
         case DisplayOrientations::LandscapeFlipped:
             rotation = DXGI_MODE_ROTATION_ROTATE180;
-            data->orientationTransform3D = XMFLOAT4X4( // 180-degree Z-rotation
+            data->vertexShaderConstantsData.projection = XMFLOAT4X4( // 180-degree Z-rotation
                 -1.0f, 0.0f, 0.0f, 0.0f,
                 0.0f, -1.0f, 0.0f, 0.0f,
                 0.0f, 0.0f, 1.0f, 0.0f,
@@ -583,9 +597,9 @@ D3D11_CreateWindowSizeDependentResources(SDL_Renderer * renderer)
 
         case DisplayOrientations::PortraitFlipped:
             rotation = DXGI_MODE_ROTATION_ROTATE90;
-            data->orientationTransform3D = XMFLOAT4X4( // 270-degree Z-rotation
-                0.0f, -1.0f, 0.0f, 0.0f,
-                1.0f, 0.0f, 0.0f, 0.0f,
+            data->vertexShaderConstantsData.projection = XMFLOAT4X4( // 90-degree Z-rotation
+                0.0f, 1.0f, 0.0f, 0.0f,
+                -1.0f, 0.0f, 0.0f, 0.0f,
                 0.0f, 0.0f, 1.0f, 0.0f,
                 0.0f, 0.0f, 0.0f, 1.0f
                 );
@@ -891,6 +905,15 @@ static int D3D11_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
         nullptr
         );
 
+    rendererData->d3dContext->UpdateSubresource(
+        rendererData->vertexShaderConstants.Get(),
+		0,
+		NULL,
+		&rendererData->vertexShaderConstantsData,
+		0,
+		0
+		);
+
     UINT stride = sizeof(VertexPositionColor);
     UINT offset = 0;
     rendererData->d3dContext->IASetVertexBuffers(
@@ -911,6 +934,12 @@ static int D3D11_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
         0
         );
 
+    rendererData->d3dContext->VSSetConstantBuffers(
+		0,
+		1,
+        rendererData->vertexShaderConstants.GetAddressOf()
+		);
+
     rendererData->d3dContext->PSSetShader(
         rendererData->pixelShader.Get(),
         nullptr,
diff --git a/src/render/direct3d11/SDL_render_d3d11_cpp.h b/src/render/direct3d11/SDL_render_d3d11_cpp.h
index 9baf3df57..3933dd735 100644
--- a/src/render/direct3d11/SDL_render_d3d11_cpp.h
+++ b/src/render/direct3d11/SDL_render_d3d11_cpp.h
@@ -24,6 +24,11 @@
 #include <DirectXMath.h>
 #include <wrl/client.h>
 
+struct SDL_VertexShaderConstants
+{
+	DirectX::XMFLOAT4X4 projection;
+};
+
 typedef struct
 {
     Microsoft::WRL::ComPtr<ID3D11Device1> d3dDevice;
@@ -39,6 +44,10 @@ typedef struct
     unsigned int vertexCount;
     bool loadingComplete;
 
+    // Vertex buffer constants:
+    SDL_VertexShaderConstants vertexShaderConstantsData;
+    Microsoft::WRL::ComPtr<ID3D11Buffer> vertexShaderConstants;
+
     // Cached renderer properties.
     DirectX::XMFLOAT2 windowSizeInDIPs;
     DirectX::XMFLOAT2 renderTargetSize;
diff --git a/src/video/windowsrt/SimpleVertexShader.hlsl b/src/video/windowsrt/SimpleVertexShader.hlsl
index adaf896e9..9065ecb03 100644
--- a/src/video/windowsrt/SimpleVertexShader.hlsl
+++ b/src/video/windowsrt/SimpleVertexShader.hlsl
@@ -1,6 +1,11 @@
 
 //#pragma pack_matrix( row_major )
 
+cbuffer SDL_VertexShaderConstants : register(b0)
+{
+	matrix projection;
+};
+
 struct VertexShaderInput
 {
     float3 pos : POSITION;
@@ -16,7 +21,14 @@ struct VertexShaderOutput
 VertexShaderOutput main(VertexShaderInput input)
 {
     VertexShaderOutput output;
-    output.pos = float4(input.pos, 1.0f);
+    float4 pos = float4(input.pos, 1.0f);
+
+    // Transform the vertex position into projected space.
+    pos = mul(pos, projection);
+    output.pos = pos;
+
+    // Pass through the texture's color without modification.
     output.tex = input.tex;
+
     return output;
 }