feat: add VR water shader (#193)

features/Water Caustics/Shaders/WaterCaustics/WaterCaustics.hlsli

@@ -4,11 +4,8 @@ struct PerPassWaterCaustics
 	float pad[3];
 };
 
-StructuredBuffer<PerPassWaterCaustics> perPassWaterCaustics : register(t71);
-
-#if defined(WATER)
-
 Texture2D<float4> WaterCaustics : register(t70);
+StructuredBuffer<PerPassWaterCaustics> perPassWaterCaustics : register(t71);
 
 float2 PanCausticsUV(float2 uv, float speed, float tiling)
 {
@@ -43,29 +40,7 @@ float3 ComputeWaterCaustics(float2 uv)
 	return caustics;
 }
 
-#else
-
-Texture2D<float4> WaterCaustics : register(t70);
-
-float2 PanCausticsUV(float2 uv, float speed, float tiling)
-{
-	return (float2(1, 0) * lightingData[0].Timer * speed) + (uv * tiling);
-}
-
-float3 SampleCaustics(float2 uv, float split)
-{
-	float2 uv1 = uv + float2(split, split);
-	float2 uv2 = uv + float2(split, -split);
-	float2 uv3 = uv + float2(-split, -split);
-
-	float r = WaterCaustics.Sample(SampColorSampler, uv1).r;
-	float g = WaterCaustics.Sample(SampColorSampler, uv2).r;
-	float b = WaterCaustics.Sample(SampColorSampler, uv3).r;
-
-	return float3(r, g, b);
-}
-
-float3 ComputeWaterCaustics(float3 waterHeight, float3 worldPosition, float3 worldSpaceNormal)
+float3 ComputeWaterCaustics(float waterHeight, float3 worldPosition, float3 worldSpaceNormal)
 {
 	float causticsDistToWater = waterHeight - worldPosition.z;
 	float shoreFactorCaustics = saturate(causticsDistToWater / 64.0);
@@ -99,5 +74,3 @@ float3 ComputeWaterCaustics(float3 waterHeight, float3 worldPosition, float3 wor
 	caustics = lerp(causticsLow, caustics, upAmount);
 	return lerp(1.0, caustics, shoreFactorCaustics * upAmount);
 }
-
-#endif

package/Shaders/Common/VR.hlsl

@@ -1,35 +1,58 @@
 /**
-Converts to the eye specific uv.
-In VR, texture buffers include the left and right eye in the same buffer. Flat only has a single camera for the entire width.
-This means the x value [0, .5] represents the left eye, and the y value (.5, 1] are the right eye.
-This returns the adjusted value
+Converts to the eye specific uv [0,1].
+In VR, texture buffers include the left and right eye in the same buffer. Flat
+only has a single camera for the entire width. This means the x value [0, .5]
+represents the left eye, and the x value (.5, 1] are the right eye. This returns
+the adjusted value
 @param uv - uv coords [0,1] to be encoded for VR
 @param a_eyeIndex The eyeIndex; 0 is left, 1 is right
+@param a_invertY Whether to invert the Y direction
 @returns uv with x coords adjusted for the VR texture buffer
 */
-float2 ConvertToStereoUV(float2 uv, uint a_eyeIndex)
+float2 ConvertToStereoUV(float2 uv, uint a_eyeIndex, uint a_invertY = 0)
 {
 #ifdef VR
 	// convert [0,1] to eye specific [0,.5] and [.5, 1] dependent on a_eyeIndex
 	uv.x = (uv.x + (float)a_eyeIndex) / 2;
+	if (a_invertY)
+		uv.y = 1 - uv.y;
 #endif
 	return uv;
 }
 
 /**
-Converts from eye specific uv to general uv.
+Converts from eye specific uv to general uv [0,1].
 In VR, texture buffers include the left and right eye in the same buffer. 
-This means the x value [0, .5] represents the left eye, and the y value (.5, 1] are the right eye.
+This means the x value [0, .5] represents the left eye, and the x value (.5, 1] are the right eye.
 This returns the adjusted value
 @param uv - eye specific uv coords [0,1]; if uv.x < 0.5, it's a left eye; otherwise right
 @param a_eyeIndex The eyeIndex; 0 is left, 1 is right
+@param a_invertY Whether to invert the Y direction
 @returns uv with x coords adjusted to full range for either left or right eye
 */
-float2 ConvertFromStereoUV(float2 uv, uint a_eyeIndex)
+float2 ConvertFromStereoUV(float2 uv, uint a_eyeIndex, uint a_invertY = 0)
 {
 #ifdef VR
 	// convert [0,.5] to [0, 1] and [.5, 1] to [0,1]
 	uv.x = 2 * uv.x - (float)a_eyeIndex;
+	if (a_invertY)
+		uv.y = 1 - uv.y;
 #endif
 	return uv;
 }
+
+/**
+Converts to the eye specific screenposition [0,Resolution].
+In VR, texture buffers include the left and right eye in the same buffer. Flat only has a single camera for the entire width.
+This means the x value [0, resx/2] represents the left eye, and the x value (resx/2, x] are the right eye.
+This returns the adjusted value
+@param screenPosition - Screenposition coords ([0,resx], [0,resy]) to be encoded for VR
+@param a_eyeIndex The eyeIndex; 0 is left, 1 is right
+@param a_resolution The resolution of the screen
+@returns screenPosition with x coords adjusted for the VR texture buffer
+*/
+float2 ConvertToStereoSP(float2 screenPosition, uint a_eyeIndex, float2 a_resolution)
+{
+	screenPosition.x /= a_resolution.x;
+	return ConvertToStereoUV(screenPosition, a_eyeIndex) * a_resolution;
+}