Add slang shaders for additional samples

shaders/slang/pbrbasic/pbr.slang

@@ -0,0 +1,138 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSInput
+{
+    float3 Pos;
+    float3 Normal;
+};
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+    float3 WorldPos;
+    float3 Normal;
+};
+
+struct UBO
+{
+    float4x4 projection;
+    float4x4 model;
+    float4x4 view;
+    float3 camPos;
+};
+ConstantBuffer<UBO> ubo;
+
+struct UBOParams {
+	float4 lights[4];
+};
+ConstantBuffer<UBOParams> uboParams;
+
+struct Material {
+	[[vk::offset(12)]] float roughness;
+	[[vk::offset(16)]] float metallic;
+	[[vk::offset(20)]] float r;
+	[[vk::offset(24)]] float g;
+	[[vk::offset(28)]] float b;
+};
+[[vk::push_constant]] Material material;
+
+static const float PI = 3.14159265359;
+
+// Normal Distribution function --------------------------------------
+float D_GGX(float dotNH, float roughness)
+{
+	float alpha = roughness * roughness;
+	float alpha2 = alpha * alpha;
+	float denom = dotNH * dotNH * (alpha2 - 1.0) + 1.0;
+	return (alpha2)/(PI * denom*denom);
+}
+
+// Geometric Shadowing function --------------------------------------
+float G_SchlicksmithGGX(float dotNL, float dotNV, float roughness)
+{
+	float r = (roughness + 1.0);
+	float k = (r*r) / 8.0;
+	float GL = dotNL / (dotNL * (1.0 - k) + k);
+	float GV = dotNV / (dotNV * (1.0 - k) + k);
+	return GL * GV;
+}
+
+// Fresnel function ----------------------------------------------------
+float3 F_Schlick(float cosTheta, Material material)
+{
+    float3 F0 = lerp(float3(0.04, 0.04, 0.04), float3(material.r, material.g, material.b), material.metallic); // * material.specular
+	float3 F = F0 + (1.0 - F0) * pow(1.0 - cosTheta, 5.0);
+	return F;
+}
+
+// Specular BRDF composition --------------------------------------------
+
+float3 BRDF(float3 L, float3 V, float3 N, Material material)
+{
+	// Precalculate vectors and dot products
+	float3 H = normalize (V + L);
+	float dotNV = clamp(dot(N, V), 0.0, 1.0);
+	float dotNL = clamp(dot(N, L), 0.0, 1.0);
+	float dotLH = clamp(dot(L, H), 0.0, 1.0);
+	float dotNH = clamp(dot(N, H), 0.0, 1.0);
+
+	// Light color fixed
+	float3 lightColor = float3(1.0, 1.0, 1.0);
+
+	float3 color = float3(0.0, 0.0, 0.0);
+
+	if (dotNL > 0.0)
+    {
+        float rroughness = max(0.05, material.roughness);
+        // D = Normal distribution (Distribution of the microfacets)
+        float D = D_GGX(dotNH, material.roughness);
+		// G = Geometric shadowing term (Microfacets shadowing)
+		float G = G_SchlicksmithGGX(dotNL, dotNV, rroughness);
+        // F = Fresnel factor (Reflectance depending on angle of incidence)
+        float3 F = F_Schlick(dotNV, material);
+
+		float3 spec = D * F * G / (4.0 * dotNL * dotNV);
+
+		color += spec * dotNL * lightColor;
+	}
+
+	return color;
+}
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input, uniform float3 objPos)
+{
+    VSOutput output;
+    float3 locPos = mul(ubo.model, float4(input.Pos, 1.0)).xyz;
+    output.WorldPos = locPos + objPos;
+    output.Normal = mul((float3x3)ubo.model, input.Normal);
+    output.Pos = mul(ubo.projection, mul(ubo.view, float4(output.WorldPos, 1.0)));
+    return output;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input)
+{
+	float3 N = normalize(input.Normal);
+	float3 V = normalize(ubo.camPos - input.WorldPos);
+
+	// Specular contribution
+	float3 Lo = float3(0.0, 0.0, 0.0);
+	for (int i = 0; i < 4; i++) {
+		float3 L = normalize(uboParams.lights[i].xyz - input.WorldPos);
+		Lo += BRDF(L, V, N, material);
+	};
+
+	// Combine with ambient
+	float3 color = float3(material.r, material.g, material.b) * 0.02;
+	color += Lo;
+
+	// Gamma correct
+	color = pow(color, float3(0.4545, 0.4545, 0.4545));
+
+	return float4(color, 1.0);
+}