#include "../../Lighting/Lighting.hlsl"
RWTexture2D<float4> _DeferredShadowTextureUAV;
float _DirectionalShadowIndex;
CBUFFER_START(DeferredShadowParameters)
float _DirectionalShadowIndex;
float3 _LightDirection;
float4 _ScreenSpaceShadowsParameters;
CBUFFER_END
#define _ContactShadowLength _ScreenSpaceShadowsParameters.x
#define _ContactShadowDistanceScaleFactor _ScreenSpaceShadowsParameters.y
#define _ContactShadowFadeEnd _ScreenSpaceShadowsParameters.z
#define _ContactShadowFadeOneOverRange _ScreenSpaceShadowsParameters.w
// Return 1.0 if occluded 0.0 if not
float4 ScreenSpaceShadowRayCast(float3 positionWS, float3 rayDirection, float rayLength)
{
int stepCount = 8;
uint3 hashInput = uint3(abs(GetAbsolutePositionWS(positionWS))* 5000);
// Dither pattern is shifted by 0.5 because we want to jitter the ray starting position backward and forward (so we need values between -0.5 and 0.5)
float ditherBias = 0.5;
float dither = GenerateHashedRandomFloat(hashInput) - ditherBias;
float3 rayStartWS = positionWS;
float3 rayEndWS = rayStartWS + rayDirection * rayLength;
float4 rayStartCS = TransformWorldToHClip(rayStartWS);
float4 rayEndCS = TransformWorldToHClip(rayEndWS);
// Here we compute a ray perpendicular to view space. This is the ray we use to compute the threshold for rejecting samples.
// This is done this way so that the threshold is less dependent of ray slope.
float4 rayOrthoViewSpace = rayStartCS + mul(GetViewToHClipMatrix(), float4(0, 0, rayLength, 0));
rayOrthoViewSpace = rayOrthoViewSpace / rayOrthoViewSpace.w;
rayStartCS.xyz = rayStartCS.xyz / rayStartCS.w;
rayEndCS.xyz = rayEndCS.xyz / rayEndCS.w;
// Pixel to light ray in clip space.
float3 rayCS = rayEndCS.xyz - rayStartCS.xyz;
// Depth at the start of the ray
float startDepth = rayStartCS.z;
// Depth range of the ray
float rayDepth = rayCS.z;
// Starting UV of the sampling loop
float2 startUV = rayStartCS.xy * 0.5f + 0.5f;
startUV.y = 1.0 - startUV.y;
// Pixel to light ray in
float2 rayUV = rayCS.xy * 0.5f;
rayUV.y = -rayUV.y;
float step = 1.0 / stepCount;
float compareThreshold = abs( rayOrthoViewSpace.z - rayStartCS.z ) * step ;
float FirstHitTime = -1.0;
[unroll]
for( int i = 0; i < stepCount; i++ )
{
// Step for this sample
float sampleStep = ((i + 1) * step + step * dither);
// UVs for the current sample
float2 sampleUV = startUV + rayUV * sampleStep;
// Ray depth for this sample
float raySampleDepth = startDepth + rayDepth * sampleStep;
// Depth buffer depth for this sample
float sampleDepth = SAMPLE_TEXTURE2D_LOD(_MainDepthTexture, sampler_MainDepthTexture, sampleUV, 0.0).x;
bool Hit = false;
float depthDiff = sampleDepth - raySampleDepth;
Hit = depthDiff < compareThreshold && depthDiff > 0.0;// 1e-4;
FirstHitTime = (Hit && FirstHitTime < 0.0) ? 1.0 : FirstHitTime;
}
float occluded = FirstHitTime > 0.0 ? 1.0 : 0.0;
// Off screen masking
//float2 Vignette = max(6.0 * abs(RayStartScreen.xy + RayStepScreen.xy * FirstHitTime) - 5.0, 0.0);
//Shadow *= saturate( 1.0 - dot( Vignette, Vignette ) );
return occluded;
}
float hash( float2 input )
{
return frac( 1.0e4 * sin( 17.0*input.x + 0.1*input.y ) *( 0.1 + abs( sin( 13.0*input.y + input.x ))));
}
float hash3D( float3 input )
{
return hash( float2( hash( input.xy ), input.z ) );
}
[numthreads(DEFERRED_SHADOW_TILE_SIZE, DEFERRED_SHADOW_TILE_SIZE, 1)]
void DeferredDirectionalShadow(uint2 groupThreadId : SV_GroupThreadID, uint2 groupId : SV_GroupID)
{
ShadowContext shadowContext = InitShadowContext();
float shadow = GetDirectionalShadowAttenuation(shadowContext, posInput.positionWS, float3(0.0, 0.0, 0.0), (uint)_DirectionalShadowIndex, float3(0.0, 0.0, 0.0));
_DeferredShadowTextureUAV[pixelCoord] = float4(shadow.xxx, 0.0);
float4 result = ScreenSpaceShadowRayCast(posInput.positionWS, normalize(_LightDirection), _ContactShadowLength * max(0.5, posInput.depthVS * _ContactShadowDistanceScaleFactor));
float contactShadow = 1.0 - result.x * saturate((_ContactShadowFadeEnd - posInput.depthVS) * _ContactShadowFadeOneOverRange);
_DeferredShadowTextureUAV[pixelCoord] = float4(shadow.x * contactShadow, 0.0, 0.0, 0.0);
//_DeferredShadowTextureUAV[pixelCoord] = contactShadow;
}
Julien Ignace
7 年前