From e98e46164c67db2d755ed32648676803920767c8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Leclercq?= <lynix680@gmail.com>
Date: Mon, 2 Aug 2021 11:14:21 +0200
Subject: [PATCH] PhysicsDemo: Add support of alpha testing to depth-prepass

---
 bin/resources/depth_pass.nzsl | 92 +++++++++++++++++++++++++++++++++++
 bin/resources/depth_vert.nzsl | 53 --------------------
 examples/PhysicsDemo/main.cpp |  8 ++-
 3 files changed, 99 insertions(+), 54 deletions(-)
 create mode 100644 bin/resources/depth_pass.nzsl
 delete mode 100644 bin/resources/depth_vert.nzsl

diff --git a/bin/resources/depth_pass.nzsl b/bin/resources/depth_pass.nzsl
new file mode 100644
index 000000000..c15edf127
--- /dev/null
+++ b/bin/resources/depth_pass.nzsl
@@ -0,0 +1,92 @@
+option HAS_DIFFUSE_TEXTURE: bool;
+option HAS_ALPHA_TEXTURE: bool;
+option ALPHA_TEST: bool;
+
+const HasUV = ALPHA_TEST && (HAS_DIFFUSE_TEXTURE || HAS_ALPHA_TEXTURE);
+
+[layout(std140)]
+struct BasicSettings
+{
+	AlphaThreshold: f32,
+	DiffuseColor: vec4<f32>
+}
+
+[layout(std140)]
+struct InstanceData
+{
+	worldMatrix: mat4<f32>,
+	invWorldMatrix: mat4<f32>
+}
+
+[layout(std140)]
+struct ViewerData
+{
+	projectionMatrix: mat4<f32>,
+	invProjectionMatrix: mat4<f32>,
+	viewMatrix: mat4<f32>,
+	invViewMatrix: mat4<f32>,
+	viewProjMatrix: mat4<f32>,
+	invViewProjMatrix: mat4<f32>,
+	renderTargetSize: vec2<f32>,
+	invRenderTargetSize: vec2<f32>,
+	eyePosition: vec3<f32>
+}
+
+external
+{
+	[set(0), binding(0)] viewerData: uniform<ViewerData>,
+	[set(1), binding(0)] instanceData: uniform<InstanceData>,
+	[set(2), binding(0)] settings: uniform<BasicSettings>,
+	[set(2), binding(2)] MaterialAlphaMap: sampler2D<f32>,
+}
+
+// Fragment stage
+struct FragIn
+{
+	[location(0), cond(HasUV)] uv: vec2<f32>
+}
+
+[entry(frag), cond(ALPHA_TEST)]
+fn main(input: FragIn)
+{
+	let alpha = settings.DiffuseColor.a;
+	const if (HAS_DIFFUSE_TEXTURE)
+		// TODO: alpha *= MaterialDiffuseMap.Sample(input.uv).a;
+		alpha = alpha * MaterialDiffuseMap.Sample(input.uv).a;
+
+	const if (HAS_ALPHA_TEXTURE)
+		// TODO: alpha *= MaterialAlphaMap.Sample(input.uv).x
+		alpha = alpha * MaterialAlphaMap.Sample(input.uv).x;
+
+	// TODO: const assert?
+	if (alpha < settings.AlphaThreshold)
+		discard;
+}
+
+[entry(frag), cond(!ALPHA_TEST)]
+fn main() {}
+
+// Vertex stage
+struct VertIn
+{
+	[location(0)] pos: vec3<f32>,
+	[location(1), cond(HasUV)] uv: vec2<f32>
+}
+
+struct VertOut
+{
+	[location(0), cond(HasUV)] uv: vec2<f32>,
+	[builtin(position)] position: vec4<f32>
+}
+
+[entry(vert)]
+fn main(input: VertIn) -> VertOut
+{
+	let output: VertOut;
+	output.position = viewerData.viewProjMatrix * instanceData.worldMatrix * vec4<f32>(input.pos, 1.0);
+
+	const if (HasUV)
+		output.uv = input.uv;
+
+	return output;
+}
diff --git a/bin/resources/depth_vert.nzsl b/bin/resources/depth_vert.nzsl
deleted file mode 100644
index cece2692d..000000000
--- a/bin/resources/depth_vert.nzsl
+++ /dev/null
@@ -1,53 +0,0 @@
-option HAS_DIFFUSE_TEXTURE: bool;
-option HAS_ALPHA_TEXTURE: bool;
-option ALPHA_TEST: bool;
-
-const HasUV = HAS_DIFFUSE_TEXTURE || HAS_ALPHA_TEXTURE;
-
-[layout(std140)]
-struct InstanceData
-{
-	worldMatrix: mat4<f32>,
-	invWorldMatrix: mat4<f32>
-}
-
-[layout(std140)]
-struct ViewerData
-{
-	projectionMatrix: mat4<f32>,
-	invProjectionMatrix: mat4<f32>,
-	viewMatrix: mat4<f32>,
-	invViewMatrix: mat4<f32>,
-	viewProjMatrix: mat4<f32>,
-	invViewProjMatrix: mat4<f32>,
-	renderTargetSize: vec2<f32>,
-	invRenderTargetSize: vec2<f32>,
-	eyePosition: vec3<f32>
-}
-
-external
-{
-	[set(0), binding(0)] viewerData: uniform<ViewerData>,
-	[set(1), binding(0)] instanceData: uniform<InstanceData>
-}
-
-// Vertex stage
-struct VertIn
-{
-	[location(0)] pos: vec3<f32>,
-	[location(1), cond(HasUV)] uv: vec2<f32>
-}
-
-struct VertOut
-{
-	[builtin(position)] position: vec4<f32>
-}
-
-[entry(vert)]
-fn main(input: VertIn) -> VertOut
-{
-	let output: VertOut;
-	output.position = viewerData.viewProjMatrix * instanceData.worldMatrix * vec4<f32>(input.pos, 1.0);
-
-	return output;
-}
diff --git a/examples/PhysicsDemo/main.cpp b/examples/PhysicsDemo/main.cpp
index 1473147d4..8b5ec3efd 100644
--- a/examples/PhysicsDemo/main.cpp
+++ b/examples/PhysicsDemo/main.cpp
@@ -79,7 +79,7 @@ int main()
 
 	auto customSettings = Nz::BasicMaterial::GetSettings()->GetBuilderData();
 	customSettings.shaders.clear();
-	customSettings.shaders.emplace_back(std::make_shared<Nz::UberShader>(Nz::ShaderStageType::Vertex, Nz::ShaderLang::Parse(resourceDir / "depth_vert.nzsl")));
+	customSettings.shaders.emplace_back(std::make_shared<Nz::UberShader>(Nz::ShaderStageType::Fragment | Nz::ShaderStageType::Vertex, Nz::ShaderLang::Parse(resourceDir / "depth_pass.nzsl")));
 
 	auto depthSettings = std::make_shared<Nz::MaterialSettings>(std::move(customSettings));
 
@@ -104,6 +104,9 @@ int main()
 	basicMat.SetDiffuseMap(Nz::Texture::LoadFromFile(resourceDir / "Spaceship/Texture/diffuse.png", texParams));
 	basicMat.SetDiffuseSampler(samplerInfo);
 
+	Nz::BasicMaterial basicMatDepth(*depthPass);
+	basicMatDepth.SetAlphaMap(Nz::Texture::LoadFromFile(resourceDir / "alphatile.png", texParams));
+
 	std::shared_ptr<Nz::Model> model = std::make_shared<Nz::Model>(std::move(gfxMesh));
 	for (std::size_t i = 0; i < model->GetSubMeshCount(); ++i)
 		model->SetMaterial(i, material);
@@ -226,7 +229,10 @@ int main()
 
 				case Nz::WindowEventType::KeyPressed:
 					if (event.key.virtualKey == Nz::Keyboard::VKey::A)
+					{
 						basicMat.EnableAlphaTest(!basicMat.IsAlphaTestEnabled());
+						basicMatDepth.EnableAlphaTest(!basicMatDepth.IsAlphaTestEnabled());
+					}
 					else if (event.key.virtualKey == Nz::Keyboard::VKey::B)
 					{
 						showColliders = !showColliders;