From 8decddbf145ca51de22ce747e8bb6c99c0a44a46 Mon Sep 17 00:00:00 2001
From: IllusionMan1212 <hisham.abourgheba@gmail.com>
Date: Thu, 2 Nov 2023 22:02:00 +0200
Subject: [PATCH] textures: add support for emission textures

---
 TODO.md             |  1 +
 shaders/frag.glsl   | 12 ++++++++++++
 src/importer/obj.rs |  3 ++-
 src/mesh.rs         | 11 +++++++----
 4 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/TODO.md b/TODO.md
index ddf8530..5301928 100644
--- a/TODO.md
+++ b/TODO.md
@@ -34,5 +34,6 @@
  - [ ] Move the invisible point lights to be around selected object from all sides so it's nicely illuminated
  - [x] Shortcuts/keybinds window under the 'Help' menu item
  - [x] Texture support (basic, but it's there)
+ - [ ] Make model loading async and show a loading indicator, instead of blocking the main thread
 
  - [ ] Bring back the regular camera movement (can maybe be a switch between them) (for later)
diff --git a/shaders/frag.glsl b/shaders/frag.glsl
index cae6e29..4af4737 100644
--- a/shaders/frag.glsl
+++ b/shaders/frag.glsl
@@ -9,6 +9,7 @@ struct Material {
   sampler2D texture_diffuse;
   sampler2D texture_specular;
   sampler2D texture_ambient;
+  sampler2D texture_emission;
 
   vec3 ambient;
   vec3 diffuse;
@@ -61,6 +62,7 @@ uniform DirLight dirLight;
 uniform PointLight pointLights[NR_POINT_LIGHTS];
 uniform SpotLight spotLight;
 uniform bool useTextures;
+uniform bool hasEmissionTexture;
 
 vec3 CalculateDirLight(DirLight light, vec3 normal, vec3 viewDir) {
   vec3 lightDir = normalize(-light.direction);
@@ -181,6 +183,12 @@ vec3 CalculateSpotLight(SpotLight light, vec3 normal, vec3 fragPos, vec3 viewDir
 
 void main()
 {
+  // discard completely transparent fragments, such as the ones used in
+  // leaves or grass textures
+  if (texture(material.texture_diffuse, texCoords).a == 0.0) {
+    discard;
+  }
+
   vec3 norm = normalize(fragNormals);
   vec3 viewDir = normalize(viewPos - fragPos);
 
@@ -194,6 +202,10 @@ void main()
 
   result += CalculateSpotLight(spotLight, norm, fragPos, viewDir);
 
+  if (useTextures && hasEmissionTexture) {
+    result += texture(material.texture_emission, texCoords).rgb;
+  }
+
   FragColor = vec4(result, material.opacity);
 }
 
diff --git a/src/importer/obj.rs b/src/importer/obj.rs
index a762a0b..2baf7bc 100644
--- a/src/importer/obj.rs
+++ b/src/importer/obj.rs
@@ -144,7 +144,8 @@ fn parse_mtl(path: &PathBuf, obj_textures: &mut HashMap<String, Texture>) -> Res
                 }
                 Some(MtlToken::DiffuseTexture)
                 | Some(MtlToken::AmbientTexture)
-                | Some(MtlToken::SpecularTexture) => {
+                | Some(MtlToken::SpecularTexture)
+                | Some(MtlToken::EmissiveTexture) => {
                     let tex_type = TextureType::from_material_str(token).unwrap();
 
                     let name = iter.next().unwrap().to_string();
diff --git a/src/mesh.rs b/src/mesh.rs
index dcf7564..906b718 100644
--- a/src/mesh.rs
+++ b/src/mesh.rs
@@ -126,7 +126,7 @@ impl Mesh {
             shader.set_3fv("material.ambient", self.material.ambient_color);
             shader.set_3fv("material.diffuse", self.material.diffuse_color);
             shader.set_3fv("material.specular", self.material.specular_color);
-            shader.set_float("material.shininess", 32.0);
+            shader.set_float("material.shininess", self.material.specular_exponent);
             shader.set_float("material.opacity", self.material.opacity);
         } else {
             shader.set_3fv("material.ambient", glm::vec3(0.0, 0.0, 0.0));
@@ -136,6 +136,7 @@ impl Mesh {
         if show_textures {
             shader.set_bool("useTextures", self.material.textures.len() > 0);
             for (i, tex) in self.material.textures.iter().enumerate() {
+                shader.set_bool("hasEmissionTexture", false);
                 unsafe {
                     gl::ActiveTexture(gl::TEXTURE0 + i as u32);
                     match tex.typ {
@@ -146,11 +147,13 @@ impl Mesh {
                             shader.set_int("material.texture_diffuse", i as i32);
                         },
                         TextureType::Specular => {
-                            shader.set_int("material.texture_specular{}", i as i32);
+                            shader.set_int("material.texture_specular", i as i32);
                         },
-                        _ => {
-                            warn!("Unsupported texture type: {:?}", tex.typ);
+                        TextureType::Emissive => {
+                            shader.set_int("material.texture_emission", i as i32);
+                            shader.set_bool("hasEmissionTexture", true);
                         },
+                        _ => {},
                     }
 
                     gl::BindTexture(gl::TEXTURE_2D, tex.id);