cCamera: Make flexible Camera struct

Author: papadanku

shaders/cAutoExposure.fx

@@ -98,9 +98,13 @@ float4 PS_Blit(VS2PS_Quad Input) : SV_TARGET0
 
 float3 PS_Exposure(VS2PS_Quad Input) : SV_TARGET0
 {
+    // Get textures
     float Luma = tex2Dlod(SampleLumaTex, float4(Input.Tex0, 0.0, 99.0)).r;
     float4 NonExposedColor = tex2D(CShade_SampleColorTex, Input.Tex0);
-    float3 ExposedColor = ApplyAutoExposure(NonExposedColor.rgb, Luma);
+
+    // Get exposure data
+    Exposure ExposureData = GetExposureData(Luma);
+    float3 ExposedColor = ApplyAutoExposure(NonExposedColor.rgb, ExposureData);
 
     float2 UNormPos = (Input.Tex0 * 2.0) - 1.0;
     float3 Output = ApplyOutputTonemap(ExposedColor.rgb);
@@ -137,7 +141,8 @@ float3 PS_Exposure(VS2PS_Quad Input) : SV_TARGET0
 
     if (_DisplayAverageLuma)
     {
-        float2 LumaTex = UNormPos + float2(0.0, -0.5);
+        // The offset goes from [-0.5, 0.5], hence the -0.5 subtraction.
+        float2 LumaTex = UNormPos + float2(0.0, 0.5);
 
         // Shrink the UV so [-1, 1] fills a square
         #if BUFFER_WIDTH > BUFFER_HEIGHT
@@ -154,7 +159,7 @@ float3 PS_Exposure(VS2PS_Quad Input) : SV_TARGET0
         // Create LumaIcon through alpha compositing
         float4 LumaIcon = 0.0;
         float4 Shadow = float4(0.0, 0.0, 0.0, 1.0);
-        float4 ExpLuma = float4((float3)exp(Luma), 1.0);
+        float4 ExpLuma = float4((float3)ExposureData.ExpLuma, 1.0);
 
         LumaIcon = lerp(LumaIcon, Shadow, ShadowMask);
         LumaIcon = lerp(ExpLuma, LumaIcon, LumaTexMask);

shaders/cBloom.fx

@@ -174,7 +174,8 @@ float4 PS_Prefilter(VS2PS_Quad Input) : SV_TARGET0
     #if USE_AUTOEXPOSURE
         // Apply auto-exposure here
         float Luma = tex2D(SampleExposureTex, Input.Tex0).r;
-        Color = ApplyAutoExposure(Color.rgb, Luma);
+        Exposure ExposureData = GetExposureData(Luma);
+        Color = ApplyAutoExposure(Color.rgb, ExposureData);
     #endif
 
     // Store log luminance in alpha channel

shaders/shared/cCamera.fxh

@@ -43,18 +43,31 @@
             ui_label = "Exposure Compensation Range";
             ui_type = "slider";
             ui_step = 0.001;
-            ui_min = 0.0;
+            ui_min = 1.0;
             ui_max = 4.0;
         > = 1.0;
 
-        float3 ApplyAutoExposure(float3 Color, float Luma)
+        struct Exposure
         {
-            float LumaAverage = exp(Luma);
-            float Ev100 = log2(LumaAverage * 100.0 / 12.5);
-            Ev100 -= _CShadeExposureBias; // optional manual bias
-            Ev100 = clamp(Ev100, -_CShadeExposureRange, _CShadeExposureRange);
-            float Exposure = 1.0 / (1.2 * exp2(Ev100));
-            return Color * Exposure;
+            float ExpLuma;
+            float Ev100;
+            float Value;
+        };
+
+        Exposure GetExposureData(float LumaTex)
+        {
+            Exposure Output;
+            Output.ExpLuma = exp(LumaTex);
+            Output.Ev100 = log2(Output.ExpLuma * 100.0 / 12.5);
+            Output.Ev100 -= _CShadeExposureBias; // optional manual bias
+            Output.Ev100 = clamp(Output.Ev100, -_CShadeExposureRange, _CShadeExposureRange);
+            Output.Value = 1.0 / (1.2 * exp2(Output.Ev100));
+            return Output;
+        }
+
+        float3 ApplyAutoExposure(float3 Color, Exposure Input)
+        {
+            return Color * Input.Value;
         }
     #endif