80 lines
2.7 KiB
HLSL
80 lines
2.7 KiB
HLSL
// XC_BUILTIN_SKYBOX_D3D12_PS
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Texture2D gSkyboxPanoramicTexture : register(t0);
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TextureCube gSkyboxTexture : register(t1);
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SamplerState gLinearSampler : register(s0);
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cbuffer EnvironmentConstants : register(b0) {
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float4 gSkyboxTopColor;
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float4 gSkyboxHorizonColor;
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float4 gSkyboxBottomColor;
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float4 gCameraRightAndTanHalfFov;
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float4 gCameraUpAndAspect;
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float4 gCameraForwardAndUnused;
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}
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cbuffer MaterialConstants : register(b1) {
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float4 gSkyboxTintAndExposure;
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float4 gSkyboxRotationAndMode;
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}
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struct PSInput {
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float4 position : SV_POSITION;
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float2 ndc : TEXCOORD0;
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};
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static const float XC_PI = 3.14159265358979323846f;
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static const float XC_INV_PI = 0.31830988618379067154f;
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static const float XC_INV_TWO_PI = 0.15915494309189533577f;
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float3 EvaluateProceduralSkybox(float3 viewRay) {
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const float vertical = clamp(viewRay.y, -1.0f, 1.0f);
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float3 color = gSkyboxHorizonColor.rgb;
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if (vertical >= 0.0f) {
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color = lerp(gSkyboxHorizonColor.rgb, gSkyboxTopColor.rgb, pow(saturate(vertical), 0.65f));
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} else {
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color = lerp(gSkyboxHorizonColor.rgb, gSkyboxBottomColor.rgb, pow(saturate(-vertical), 0.55f));
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}
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return color;
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}
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float3 RotateAroundY(float3 viewRay) {
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const float rotation = gSkyboxRotationAndMode.x;
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const float sinTheta = sin(rotation);
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const float cosTheta = cos(rotation);
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return normalize(float3(
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viewRay.x * cosTheta - viewRay.z * sinTheta,
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viewRay.y,
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viewRay.x * sinTheta + viewRay.z * cosTheta));
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}
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float2 ComputePanoramicUv(float3 viewRay) {
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const float3 rotatedRay = RotateAroundY(viewRay);
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const float u = frac(atan2(rotatedRay.z, rotatedRay.x) * XC_INV_TWO_PI + 0.5f);
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const float v = acos(clamp(rotatedRay.y, -1.0f, 1.0f)) * XC_INV_PI;
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return float2(u, saturate(v));
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}
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float4 MainPS(PSInput input) : SV_Target {
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const float tanHalfFov = gCameraRightAndTanHalfFov.w;
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const float aspect = gCameraUpAndAspect.w;
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float3 viewRay = normalize(
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gCameraForwardAndUnused.xyz +
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input.ndc.x * aspect * tanHalfFov * gCameraRightAndTanHalfFov.xyz +
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input.ndc.y * tanHalfFov * gCameraUpAndAspect.xyz);
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float3 color = EvaluateProceduralSkybox(viewRay);
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if (gSkyboxRotationAndMode.y > 1.5f) {
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color = gSkyboxTexture.Sample(gLinearSampler, RotateAroundY(viewRay)).rgb *
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gSkyboxTintAndExposure.rgb *
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gSkyboxTintAndExposure.w;
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} else if (gSkyboxRotationAndMode.y > 0.5f) {
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color = gSkyboxPanoramicTexture.Sample(gLinearSampler, ComputePanoramicUv(viewRay)).rgb *
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gSkyboxTintAndExposure.rgb *
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gSkyboxTintAndExposure.w;
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}
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return float4(color, 1.0f);
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}
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