feat: gamma functionality on windows64

4J_Render/Windows64/shaders/screen_PS.hlsl

@@ -26,6 +26,11 @@ cbuffer cbuff : register(b4)
     float4 clearColour;
 };
 
+cbuffer gammaBuff : register(b6)
+{
+    float4 gammaParams;
+};
+
 SamplerState screen_sampler_s : register(s0);
 Texture2D<float4> screen_texture : register(t0);
 
@@ -37,4 +42,12 @@ float4 PS_ScreenSpace(float4 position : SV_POSITION, float2 texcoord : TEXCOORD0
 float4 PS_ScreenClear(float4 position : SV_POSITION) : SV_TARGET
 {
     return clearColour;
+}
+
+float4 PS_ScreenGamma(float4 position : SV_POSITION, float2 texcoord : TEXCOORD0) : SV_TARGET
+{
+    float4 colour = screen_texture.Sample(screen_sampler_s, texcoord);
+    float invGamma = gammaParams.x;
+    colour.rgb = pow(saturate(colour.rgb), invGamma);
+    return colour;
 }