[hud] Enable manual sRGB conversion for non-sRGB swap chains

We still blend in the wrong color space, but text should be a bit
more readable in some games now.

src/d3d11/d3d11_swapchain.cpp

@@ -335,7 +335,7 @@ namespace dxvk {
       m_context->draw(3, 1, 0, 0);
 
       if (m_hud != nullptr)
-        m_hud->render(m_context, info.imageExtent);
+        m_hud->render(m_context, info.format, info.imageExtent);
       
       if (i + 1 >= SyncInterval)
         m_context->signal(m_frameLatencySignal, frameId);

src/dxvk/hud/dxvk_hud.cpp

@@ -53,13 +53,17 @@ namespace dxvk::hud {
   }
   
   
-  void Hud::render(const Rc<DxvkContext>& ctx, VkExtent2D surfaceSize) {
+  void Hud::render(
+    const Rc<DxvkContext>&  ctx,
+          VkSurfaceFormatKHR surfaceFormat,
+          VkExtent2D        surfaceSize) {
     m_uniformData.surfaceSize = surfaceSize;
     
     this->updateUniformBuffer(ctx, m_uniformData);
 
-    this->setupRendererState(ctx);
+    this->setupRendererState(ctx, surfaceFormat);
     this->renderHudElements(ctx);
+    this->resetRendererState(ctx);
   }
   
   
@@ -68,17 +72,27 @@ namespace dxvk::hud {
   }
 
 
-  void Hud::setupRendererState(const Rc<DxvkContext>& ctx) {
+  void Hud::setupRendererState(
+    const Rc<DxvkContext>&  ctx,
+          VkSurfaceFormatKHR surfaceFormat) {
+    bool isSrgb = imageFormatInfo(surfaceFormat.format)->flags.test(DxvkFormatFlag::ColorSpaceSrgb);
+
     ctx->setRasterizerState(m_rsState);
     ctx->setBlendMode(0, m_blendMode);
 
     ctx->bindResourceBuffer(0,
       DxvkBufferSlice(m_uniformBuffer));
 
+    ctx->setSpecConstant(VK_PIPELINE_BIND_POINT_GRAPHICS, 0, isSrgb);
     m_renderer.beginFrame(ctx, m_uniformData.surfaceSize);
   }
 
 
+  void Hud::resetRendererState(const Rc<DxvkContext>& ctx) {
+    ctx->setSpecConstant(VK_PIPELINE_BIND_POINT_GRAPHICS, 0, 0);
+  }
+
+
   void Hud::renderHudElements(const Rc<DxvkContext>& ctx) {
     m_hudItems.render(m_renderer);
   }

src/dxvk/hud/dxvk_hud.h

@@ -45,8 +45,9 @@ namespace dxvk::hud {
      * \param [in] surfaceSize Image size, in pixels
      */
     void render(
-      const Rc<DxvkContext>& ctx,
-            VkExtent2D       surfaceSize);
+      const Rc<DxvkContext>&  ctx,
+            VkSurfaceFormatKHR surfaceFormat,
+            VkExtent2D        surfaceSize);
 
     /**
      * \brief Adds a HUD item if enabled
@@ -85,6 +86,10 @@ namespace dxvk::hud {
     HudItemSet            m_hudItems;
 
     void setupRendererState(
+      const Rc<DxvkContext>&  ctx,
+            VkSurfaceFormatKHR surfaceFormat);
+
+    void resetRendererState(
       const Rc<DxvkContext>&  ctx);
 
     void renderHudElements(

src/dxvk/hud/shaders/hud_line_frag.frag

@@ -1,10 +1,23 @@
 #version 450
 
+layout(constant_id = 1249) const bool srgbSwapchain = false;
+
 layout(location = 0) in  vec4 v_color;
 layout(location = 0) out vec4 o_color;
 
+vec3 linearToSrgb(vec3 color) {
+  bvec3 isLo = lessThanEqual(color, vec3(0.0031308f));
+
+  vec3 loPart = color * 12.92f;
+  vec3 hiPart = pow(color, vec3(5.0f / 12.0f)) * 1.055f - 0.055f;
+  return mix(hiPart, loPart, isLo);
+}
+
 void main() {
   o_color = vec4(
     v_color.rgb * v_color.a,
     v_color.a);
+
+  if (!srgbSwapchain)
+    o_color.rgb = linearToSrgb(o_color.rgb);
 }

src/dxvk/hud/shaders/hud_text_frag.frag

@@ -1,5 +1,8 @@
 #version 450
 
+layout(constant_id = 1249) const bool srgbSwapchain = false;
+
+layout(set = 0, binding = 0) uniform texture2D s_base;
 layout(set = 0, binding = 1) uniform sampler2D s_font;
 
 layout(location = 0) in vec2 v_texcoord;
@@ -10,6 +13,14 @@ uniform push_data {
   vec4 color;
 };
 
+vec3 linearToSrgb(vec3 color) {
+  bvec3 isLo = lessThanEqual(color, vec3(0.0031308f));
+
+  vec3 loPart = color * 12.92f;
+  vec3 hiPart = pow(color, vec3(5.0f / 12.0f)) * 1.055f - 0.055f;
+  return mix(hiPart, loPart, isLo);
+}
+
 float sampleAlpha(float alpha_bias, float dist_range) {
   float value = texture(s_font, v_texcoord).r + alpha_bias - 0.5f;
   float dist  = value * dot(vec2(dist_range, dist_range), 1.0f / fwidth(v_texcoord.xy));
@@ -25,4 +36,7 @@ void main() {
   
   o_color = mix(r_shadow, r_center, r_alpha_center);
   o_color.rgb *= o_color.a;
+
+  if (!srgbSwapchain)
+    o_color.rgb = linearToSrgb(o_color.rgb);
 }