From b080ced82df543faa0d7b780a1a198c5edbc43d4 Mon Sep 17 00:00:00 2001
From: Momchil Atanasov <momchil.dev@gmail.com>
Date: Sun, 29 Sep 2024 03:25:22 +0300
Subject: [PATCH] Add support for metallic-roughness textures

---
 game/asset/dsl/provider_model.go | 23 +++++++++++++++++------
 game/asset/mdl/converter.go      |  2 +-
 game/asset/mdl/texture.go        |  9 +++++++++
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/game/asset/dsl/provider_model.go b/game/asset/dsl/provider_model.go
index d5db0b32..7416ae68 100644
--- a/game/asset/dsl/provider_model.go
+++ b/game/asset/dsl/provider_model.go
@@ -213,6 +213,8 @@ func BuildModelResource(gltfDoc *gltf.Document, forceCollision bool) (*mdl.Model
 			}
 			if texIndex := gltfutil.MetallicRoughnessTextureIndex(gltfDoc, gltfPBR); texIndex != nil {
 				metallicRoughnessTextureIndex = texIndex
+				sampler := samplersFromIndex[*texIndex]
+				sampler.Texture().SetLinear(true)
 			}
 		} else {
 			color = sprec.NewVec4(1.0, 1.0, 1.0, 1.0)
@@ -771,17 +773,26 @@ func createPBRShader(cfg pbrShaderConfig) string {
 
 	if cfg.hasAlphaTesting {
 		sourceCode += `
-				if #color.a < alphaThreshold {
-					discard
-				}
+			if #color.a < alphaThreshold {
+				discard
+			}
 		`
 	}
 
-	sourceCode += `
+	if cfg.hasMetallicRoughnessTexture {
+		sourceCode += `
+			var metallicRoughness vec4 = sample(metallicRoughnessSampler, #vertexUV)
+			#metallic = metallicRoughness.b
+			#roughness = metallicRoughness.g
+		`
+	} else {
+		sourceCode += `
 			#metallic = metallic
 			#roughness = roughness
-		}
-	`
+		`
+	}
+
+	sourceCode += `}`
 
 	return sourceCode
 }
diff --git a/game/asset/mdl/converter.go b/game/asset/mdl/converter.go
index 59f95b85..e2700e43 100644
--- a/game/asset/mdl/converter.go
+++ b/game/asset/mdl/converter.go
@@ -837,7 +837,7 @@ func (c *Converter) convertTexture(texture *Texture) (uint32, error) {
 	default:
 		return 0, fmt.Errorf("unsupported texture kind %d", texture.Kind())
 	}
-	if isLikelyLinearSpace(texture.format) {
+	if isLikelyLinearSpace(texture.format) || texture.isLinear {
 		flags |= asset.TextureFlagLinearSpace
 	}
 	if texture.generateMipmaps {
diff --git a/game/asset/mdl/texture.go b/game/asset/mdl/texture.go
index 74657d38..55b80a96 100644
--- a/game/asset/mdl/texture.go
+++ b/game/asset/mdl/texture.go
@@ -45,6 +45,7 @@ type Texture struct {
 	height          int
 	format          TextureFormat
 	generateMipmaps bool
+	isLinear        bool
 	layers          []TextureLayer
 }
 
@@ -83,6 +84,14 @@ func (t *Texture) SetFormat(format TextureFormat) {
 	}
 }
 
+func (t *Texture) Linear() bool {
+	return t.isLinear
+}
+
+func (t *Texture) SetLinear(isLinear bool) {
+	t.isLinear = isLinear
+}
+
 func (t *Texture) GenerateMipmaps() bool {
 	return t.generateMipmaps
 }