From afbc3a5bb7089faf28c4f8f57495e6f0d659fe27 Mon Sep 17 00:00:00 2001
From: Sascha Willems <webmaster@saschawillems.de>
Date: Thu, 1 May 2025 12:02:19 +0200
Subject: [PATCH] Add slang shader for vertex attributes sample

---
 shaders/slang/gltfscenerendering/scene.slang |  4 -
 shaders/slang/vertexattributes/scene.slang   | 86 ++++++++++++++++++++
 2 files changed, 86 insertions(+), 4 deletions(-)
 create mode 100644 shaders/slang/vertexattributes/scene.slang

diff --git a/shaders/slang/gltfscenerendering/scene.slang b/shaders/slang/gltfscenerendering/scene.slang
index 776d37ef..b9ed1049 100644
--- a/shaders/slang/gltfscenerendering/scene.slang
+++ b/shaders/slang/gltfscenerendering/scene.slang
@@ -33,10 +33,6 @@ struct UBO
 };
 ConstantBuffer<UBO> ubo;
 
-struct PushConsts {
-	float4x4 model;
-};
-
 [[vk::binding(0, 1)]] Sampler2D samplerColorMap;
 [[vk::binding(1, 1)]] Sampler2D samplerNormalMap;
 
diff --git a/shaders/slang/vertexattributes/scene.slang b/shaders/slang/vertexattributes/scene.slang
new file mode 100644
index 00000000..39223e4e
--- /dev/null
+++ b/shaders/slang/vertexattributes/scene.slang
@@ -0,0 +1,86 @@
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+/* Copyright (c) 2025, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct VSInput
+{
+    float3 Pos;
+    float3 Normal;
+    float2 UV;
+    float4 Tangent;
+};
+
+struct VSOutput
+{
+    float4 Pos : SV_POSITION;
+    float3 Normal;
+    float2 UV;
+    float3 ViewVec;
+    float3 LightVec;
+    float4 Tangent;
+};
+
+struct UBO
+{
+    float4x4 projection;
+    float4x4 view;
+    float4 lightPos;
+    float4 viewPos;
+};
+ConstantBuffer<UBO> ubo;
+
+[[vk::binding(0, 1)]] Sampler2D samplerColorMap;
+[[vk::binding(1, 1)]] Sampler2D samplerNormalMap;
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input, uniform float4x4 modelMat)
+{
+    VSOutput output;
+    output.Normal = input.Normal;
+    output.UV = input.UV;
+    output.Tangent = input.Tangent;
+
+    float4x4 modelView = mul(ubo.view, modelMat);
+
+    output.Pos = mul(ubo.projection, mul(modelView, float4(input.Pos.xyz, 1.0)));
+
+    output.Normal = mul((float3x3)modelMat, input.Normal);
+    float4 pos = mul(modelMat, float4(input.Pos, 1.0));
+    output.LightVec = ubo.lightPos.xyz - pos.xyz;
+    output.ViewVec = ubo.viewPos.xyz - pos.xyz;
+    return output;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input, uniform float4x4 modelMat, uniform uint alphaMask, uniform float alphaMaskCutoff)
+{
+    float4 color = samplerColorMap.Sample(input.UV);
+
+    if (alphaMask == 1) {
+        if (color.a < alphaMaskCutoff) {
+            discard;
+        }
+    }
+
+    float3 N = normalize(input.Normal);
+    float3 T = normalize(input.Tangent.xyz);
+    float3 B = cross(input.Normal, input.Tangent.xyz) * input.Tangent.w;
+    float3x3 TBN = float3x3(T, B, N);
+    N = mul(normalize(samplerNormalMap.Sample(input.UV).xyz * 2.0 - float3(1.0, 1.0, 1.0)), TBN);
+
+    const float ambient = 0.1;
+    float3 L = normalize(input.LightVec);
+    float3 V = normalize(input.ViewVec);
+    float3 R = reflect(-L, N);
+    float3 diffuse = max(dot(N, L), ambient).rrr;
+    float3 specular = pow(max(dot(R, V), 0.0), 32.0);
+    return float4(diffuse * color.rgb + specular, color.a);
+}
\ No newline at end of file