// DeformationCS.usf
#include "/Engine/Public/Platform.ush"
// 输入输出定义
Texture2D<float4> InputTexture;
RWTexture2D<float4> OutputTexture;
// 参数缓冲区
cbuffer Parameters
{
	float3 ImpactPoint;
	float ImpactForce;
	float3 ImpactNormal;
	float DeformationRadius;
	float Plasticity;
	int3 TextureSize;
	int3 UpdateRegionMin;
	int3 UpdateRegionSize;
};
// 线程组大小
#define THREADGROUP_SIZE_X 8
#define THREADGROUP_SIZE_Y 8
[numthreads(THREADGROUP_SIZE_X, THREADGROUP_SIZE_Y, 1)]
void MainCS(
	uint3 GroupID : SV_GroupID,
	uint3 GroupThreadID : SV_GroupThreadID,
	uint3 DispatchThreadID : SV_DispatchThreadID
)
{
	// 计算全局像素坐标
	int2 PixelCoord = DispatchThreadID.xy + int2(UpdateRegionMin.xy);
    
	// 检查是否在有效区域内
	if (PixelCoord.x >= UpdateRegionMin.x + UpdateRegionSize.x || 
		PixelCoord.y >= UpdateRegionMin.y + UpdateRegionSize.y)
	{
		return;
	}
    
	// 从输入纹理读取位置
	float4 OriginalPos = InputTexture.Load(int3(PixelCoord, 0));
    
	// 计算到碰撞点的距离
	float dist = distance(OriginalPos.xyz, ImpactPoint);
    
	// 在变形半径内处理
	if (dist < DeformationRadius)
	{
		// 计算变形衰减 (高斯衰减)
		float falloff = exp(-(dist * dist) / (2.0 * DeformationRadius * DeformationRadius));
        
		// 计算变形量 (考虑法线方向)
		float3 deformation = ImpactNormal * ImpactForce * falloff * 0.01;
        
		// 应用塑性变形
		float3 newPos = OriginalPos.xyz + deformation * Plasticity;
        
		// 写入新位置
		OutputTexture[PixelCoord] = float4(newPos, OriginalPos.w);
	}
	else
	{
		// 保持原位置
		OutputTexture[PixelCoord] = OriginalPos;
	}
}