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添加体积阴影和光照：统一与Unity版本一致

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ssdfasd
2026-03-12 01:38:23 +08:00
parent 00f17ddd62
commit c7a8b50149
2 changed files with 77 additions and 17 deletions
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81
Res/Shader/volume.hlsl
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@@ -4,14 +4,12 @@
cbuffer CB0 : register(b1)
{
float4x4 _InverseViewProjection;
float3 _CameraPos;
float _DensityScale;
float3 _BBoxMin;
float _StepSize;
float3 _BBoxMax;
uint _MaxSteps;
float _RotationY;
float4x4 _InverseViewProjection; // 64 bytes
float4 _CameraPos_Density; // xyz = CameraPos, w = DensityScale
float4 _BBoxMin_Step; // xyz = BBoxMin, w = StepSize
float4 _BBoxMax_MaxSteps; // xyz = BBoxMax, w = MaxSteps
float4 _Rotation_Pad_LightSamples; // x = RotationY, yzw = pad, but we'll use differently
float4 _LightDir_Samples; // xyz = LightDir, w = LightSamples
};
StructuredBuffer<uint> buf : register(t1);
@@ -90,6 +88,47 @@ float phase_function()
return 1.0;
}
uint rand_xorshift(uint seed)
{
seed ^= (seed << 13);
seed ^= (seed >> 17);
seed ^= (seed << 5);
return seed;
}
float random_float(float3 pos)
{
uint seed = asuint(pos.x + pos.y + pos.z);
float res = float(rand_xorshift(seed)) * (1.0 / 4294967296.0);
res = float(rand_xorshift(asuint(res))) * (1.0 / 4294967296.0);
return res;
}
float volumetric_shadow(float3 pos, float densityScale, inout pnanovdb_readaccessor_t acc)
{
float lightSamples = _LightDir_Samples.w;
if (lightSamples < 1) { return 0.0; }
float3 light_dir = _LightDir_Samples.xyz;
float shadow = 1.0;
float step_size = 1.0;
int steps = 10;
for (int step = 0; step < steps; step++)
{
float3 sample_pos = pos + step_size * light_dir;
float sigmaS = get_value_coord(acc, sample_pos) * densityScale;
float sigmaE = max(0.000001, sigmaS) * 2.0;
shadow *= exp(-sigmaE * step_size);
step_size *= (2.0 + random_float(sample_pos));
}
return shadow;
}
PSInput MainVS(VSInput input)
{
PSInput output;
@@ -116,7 +155,7 @@ bool intersectBox(float3 origin, float3 dir, float3 boxMin, float3 boxMax, out f
float4 MainPS(PSInput input) : SV_TARGET
{
float3 rayDir = normalize(input.worldPos - _CameraPos);
float3 rayDir = normalize(input.worldPos - _CameraPos_Density.xyz);
float tmin = 0.01;
float tmax = 5000.0;
@@ -126,6 +165,14 @@ float4 MainPS(PSInput input) : SV_TARGET
float3 color = float3(0, 0, 0);
float transmittance = 1.0;
float acc_density = 0.0;
float3 ambient_light = 0.005;
float _DensityScale = _CameraPos_Density.w;
float _StepSize = _BBoxMin_Step.w;
float _MaxSteps = _BBoxMax_MaxSteps.w;
float _RotationY = _Rotation_Pad_LightSamples.x;
float _LightSamples = _LightDir_Samples.w;
float cosR = cos(_RotationY);
float sinR = sin(_RotationY);
@@ -135,7 +182,7 @@ float4 MainPS(PSInput input) : SV_TARGET
-sinR, 0, cosR
);
float3 localCameraPos = mul(invRotY, _CameraPos);
float3 localCameraPos = mul(invRotY, _CameraPos_Density.xyz);
float3 localRayDir = mul(invRotY, rayDir);
float not_used;
@@ -144,7 +191,7 @@ float4 MainPS(PSInput input) : SV_TARGET
float skip = 0;
for (uint i = 0; i < _MaxSteps; i++) {
for (int i = 0; i < (int)_MaxSteps; i++) {
if (tmin >= tmax || transmittance < 0.01) break;
float3 localPos = localCameraPos + localRayDir * tmin;
@@ -174,14 +221,20 @@ float4 MainPS(PSInput input) : SV_TARGET
float sigmaS = density;
float sigmaE = max(0.000001, sigmaS);
float3 S = sigmaS * phase_function() * float3(1, 1, 1);
acc_density += sigmaS;
float shadow = volumetric_shadow(localPos, _DensityScale, volume.acc);
float3 S = sigmaS * phase_function() * shadow * float3(1, 1, 1);
float3 Sint = (S - S * exp(-sigmaE * _StepSize)) / sigmaE;
color += transmittance * Sint;
transmittance *= exp(-sigmaE * _StepSize);
if (acc_density > 1.0) break;
tmin += _StepSize;
}
float alpha = 1.0 - transmittance;
return float4(color, alpha);
float3 final_color = (color + ambient_light) * acc_density;
final_color = pow(final_color, 1.0 / 2.2);
return float4(final_color, acc_density);
}

13
main.cpp
View File

@@ -290,7 +290,7 @@ int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLi
DirectX::XMFLOAT4X4 invViewProjMat;
DirectX::XMStoreFloat4x4(&invViewProjMat, invViewProj);
float volumeCBData[32];
float volumeCBData[36];
memcpy(volumeCBData, &invViewProjMat, sizeof(float) * 16);
volumeCBData[16] = -10.0f;
volumeCBData[17] = 73.0f;
@@ -303,9 +303,16 @@ int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLi
volumeCBData[24] = (float)nanoVDBData.worldBBox[3];
volumeCBData[25] = (float)nanoVDBData.worldBBox[4];
volumeCBData[26] = (float)nanoVDBData.worldBBox[5];
volumeCBData[27] = 2000;
volumeCBData[27] = 2000.0f; // MaxSteps as float
volumeCBData[28] = timeSinceAppStartInSecond * 0.3f; // RotationY
UpdateConstantBuffer(volumeCB, volumeCBData, sizeof(float) * 29);
volumeCBData[29] = 0.0f; // Pad0
volumeCBData[30] = 0.0f; // Pad1
volumeCBData[31] = 0.0f; // Pad2
volumeCBData[32] = 0.5f; // LightDir X
volumeCBData[33] = 0.8f; // LightDir Y
volumeCBData[34] = 0.3f; // LightDir Z
volumeCBData[35] = 8.0f; // LightSamples as float
UpdateConstantBuffer(volumeCB, volumeCBData, sizeof(float) * 36);
if (frameCount == 1) {
printf("Volume BBox: [%.2f, %.2f, %.2f] - [%.2f, %.2f, %.2f]\n",
volumeCBData[20], volumeCBData[21], volumeCBData[22],