Add slang shader for shadow mapping and shadow mapping cascades sample

shaders/slang/shadowmapping/offscreen.slang

@@ -0,0 +1,23 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct UBO
+{
+    float4x4 depthMVP;
+};
+ConstantBuffer<UBO> ubo;
+
+[shader("vertex")]
+float4 vertexMain(float3 Pos) : SV_POSITION
+{
+    return mul(ubo.depthMVP, float4(Pos, 1.0));
+}
+
+[shader("fragment")]
+float4 fragmentMain()
+{
+	return float4(1.0, 0.0, 0.0, 1.0);
+}

shaders/slang/shadowmapping/quad.slang

@@ -0,0 +1,48 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct UBO
+{
+	float4x4 projection;
+	float4x4 view;
+	float4x4 model;
+	float4x4 lightSpace;
+	float4 lightPos;
+	float zNear;
+	float zFar;
+};
+ConstantBuffer<UBO> ubo;
+Sampler2D samplerColor;
+
+float LinearizeDepth(float depth)
+{
+  float n = ubo.zNear;
+  float f = ubo.zFar;
+  float z = depth;
+  return (2.0 * n) / (f + n - z * (f - n));
+}
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+    float2 UV;
+};
+
+[shader("vertex")]
+VSOutput vertexMain(uint VertexIndex: SV_VertexID)
+{
+    VSOutput output;
+    output.UV = float2((VertexIndex << 1) & 2, VertexIndex & 2);
+    output.Pos = float4(output.UV * 2.0f - 1.0f, 0.0f, 1.0f);
+    return output;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+    float depth = samplerColor.Sample(input.UV).r;
+    return float4((1.0 - LinearizeDepth(depth)).xxx, 1.0);
+}

shaders/slang/shadowmapping/scene.slang

@@ -0,0 +1,116 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSInput
+{
+    float3 Pos;
+    float2 UV;
+    float3 Color;
+    float3 Normal;
+};
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+	float3 Normal;
+	float3 Color;
+	float3 ViewVec;
+	float3 LightVec;
+	float4 ShadowCoord;
+};
+
+struct UBO
+{
+    float4x4 projection;
+    float4x4 view;
+    float4x4 model;
+    float4x4 lightSpace;
+    float4 lightPos;
+    float zNear;
+    float zFar;
+};
+ConstantBuffer<UBO> ubo;
+Sampler2D shadowMapSampler;
+
+[SpecializationConstant] const int enablePCF = 0;
+
+#define ambient 0.1
+
+float textureProj(float4 shadowCoord, float2 off)
+{
+	float shadow = 1.0;
+	if ( shadowCoord.z > -1.0 && shadowCoord.z < 1.0 )
+    {
+        float dist = shadowMapSampler.Sample(shadowCoord.xy + off).r;
+		if ( shadowCoord.w > 0.0 && dist < shadowCoord.z )
+		{
+			shadow = ambient;
+		}
+	}
+	return shadow;
+}
+
+float filterPCF(float4 sc)
+{
+    int2 texDim;
+    shadowMapSampler.GetDimensions(texDim.x, texDim.y);
+	float scale = 1.5;
+	float dx = scale * 1.0 / float(texDim.x);
+	float dy = scale * 1.0 / float(texDim.y);
+
+	float shadowFactor = 0.0;
+	int count = 0;
+	int range = 1;
+
+	for (int x = -range; x <= range; x++)
+	{
+		for (int y = -range; y <= range; y++)
+		{
+			shadowFactor += textureProj(sc, float2(dx*x, dy*y));
+			count++;
+		}
+
+	}
+	return shadowFactor / count;
+}
+
+static const float4x4 biasMat = float4x4(
+    0.5, 0.0, 0.0, 0.5,
+    0.0, 0.5, 0.0, 0.5,
+    0.0, 0.0, 1.0, 0.0,
+    0.0, 0.0, 0.0, 1.0);
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input)
+{
+    VSOutput output = (VSOutput)0;
+    output.Color = input.Color;
+    output.Normal = input.Normal;
+
+    output.Pos = mul(ubo.projection, mul(ubo.view, mul(ubo.model, float4(input.Pos.xyz, 1.0))));
+
+    float4 pos = mul(ubo.model, float4(input.Pos, 1.0));
+    output.Normal = mul((float3x3)ubo.model, input.Normal);
+    output.LightVec = normalize(ubo.lightPos.xyz - input.Pos);
+    output.ViewVec = -pos.xyz;
+
+    output.ShadowCoord = mul(biasMat, mul(ubo.lightSpace, mul(ubo.model, float4(input.Pos, 1.0))));
+    return output;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+	float shadow = (enablePCF == 1) ? filterPCF(input.ShadowCoord / input.ShadowCoord.w) : textureProj(input.ShadowCoord / input.ShadowCoord.w, float2(0.0, 0.0));
+
+	float3 N = normalize(input.Normal);
+	float3 L = normalize(input.LightVec);
+	float3 V = normalize(input.ViewVec);
+	float3 R = normalize(-reflect(L, N));
+	float3 diffuse = max(dot(N, L), ambient) * input.Color;
+
+	return float4(diffuse * shadow, 1.0);
+}