feat(engine): add lighting maps

12 files changed, 261 insertions, 168 deletions

diff --git a/engine/Cargo.toml b/engine/Cargo.toml
index db30fff..b33b2d6 100644
--- a/engine/Cargo.toml
+++ b/engine/Cargo.toml
@@ -13,6 +13,7 @@ gl = "0.14.0"
 bitflags = "2.4.0"
 cstr = "0.2.11"
 tracing = { version = "0.1.39", optional = true }
+seq-macro = "0.3.5"
 
 [dependencies.image]
 version = "0.24.7"
diff --git a/engine/fragment-color.glsl b/engine/fragment-color.glsl
deleted file mode 100644
index 4213860..0000000
--- a/engine/fragment-color.glsl
+++ /dev/null
@@ -1,28 +0,0 @@
-#version 330 core
-
-#preinclude "light.glsl"
-
-out vec4 FragColor;
-
-in vec3 in_frag_color;
-in vec3 in_frag_pos;
-in vec3 in_normal;
-
-uniform vec3 view_pos;
-
-void main()
-{
-	vec3 ambient_light = calc_ambient_light();
-
-	vec3 light_direction = normalize(light.position - in_frag_pos);
-	vec3 norm = normalize(in_normal);
-
-	vec3 diffuse_light = calc_diffuse_light(light_direction, norm);
-
-	vec3 specular_light =
-		calc_specular_light(light_direction, norm, view_pos, in_frag_pos);
-
-	FragColor =
-		vec4((ambient_light + diffuse_light + specular_light) * in_frag_color, 1.0);
-}
-
diff --git a/engine/fragment-texture.glsl b/engine/fragment-texture.glsl
deleted file mode 100644
index 69718a6..0000000
--- a/engine/fragment-texture.glsl
+++ /dev/null
@@ -1,31 +0,0 @@
-#version 330 core
-
-#preinclude "light.glsl"
-
-out vec4 FragColor;
-
-in vec2 in_texture_coords;
-
-in vec3 in_frag_pos;
-in vec3 in_normal;
-
-uniform vec3 view_pos;
-
-uniform sampler2D input_texture;
-
-void main()
-{
-	vec3 ambient_light = calc_ambient_light();
-
-	vec3 light_direction = normalize(light.position - in_frag_pos);
-	vec3 norm = normalize(in_normal);
-
-	vec3 diffuse_light = calc_diffuse_light(light_direction, norm);
-
-	vec3 specular_light =
-		calc_specular_light(light_direction, norm, view_pos, in_frag_pos);
-
-	vec4 light = vec4((ambient_light + diffuse_light + specular_light), 1.0);
-
-	FragColor = light * texture(input_texture, in_texture_coords);
-}
diff --git a/engine/fragment.glsl b/engine/fragment.glsl
new file mode 100644
index 0000000..428e87f
--- /dev/null
+++ b/engine/fragment.glsl
@@ -0,0 +1,34 @@
+#version 330 core
+
+#preinclude "light.glsl"
+
+out vec4 FragColor;
+
+in vec2 in_texture_coords;
+
+in vec3 in_frag_pos;
+in vec3 in_normal;
+
+uniform vec3 view_pos;
+
+uniform sampler2D input_texture;
+
+void main()
+{
+	vec3 ambient_light = calc_ambient_light(in_texture_coords);
+
+	vec3 light_direction = normalize(light.position - in_frag_pos);
+	vec3 norm = normalize(in_normal);
+
+	vec3 diffuse_light = calc_diffuse_light(light_direction, norm, in_texture_coords);
+
+	vec3 specular_light = calc_specular_light(
+		light_direction,
+		norm,
+		view_pos,
+		in_frag_pos,
+		in_texture_coords
+	);
+
+	FragColor = vec4((ambient_light + diffuse_light + specular_light), 1.0);
+}
diff --git a/engine/light.glsl b/engine/light.glsl
index 90539a1..3ba5ba0 100644
--- a/engine/light.glsl
+++ b/engine/light.glsl
@@ -4,9 +4,9 @@
 #define LIGHT_GLSL
 
 struct Material {
-    vec3 ambient;
-    vec3 diffuse;
-    vec3 specular;
+    sampler2D ambient;
+    sampler2D diffuse;
+    sampler2D specular;
     float shininess;
 }; 
 
@@ -21,23 +21,24 @@ struct Light {
 uniform Material material;
 uniform Light light;
 
-vec3 calc_ambient_light()
+vec3 calc_ambient_light(in vec2 texture_coords)
 {
-	return light.ambient * material.ambient;
+	return light.ambient * vec3(texture(material.ambient, texture_coords));
 }
 
-vec3 calc_diffuse_light(in vec3 light_dir, in vec3 norm)
+vec3 calc_diffuse_light(in vec3 light_dir, in vec3 norm, in vec2 texture_coords)
 {
 	float diff = max(dot(norm, light_dir), 0.0);
 
-	return light.diffuse * (diff * material.diffuse);
+	return light.diffuse * (diff * vec3(texture(material.diffuse, texture_coords)));
 }
 
 vec3 calc_specular_light(
 	in vec3 light_dir,
 	in vec3 norm,
 	in vec3 view_pos,
-	in vec3 frag_pos
+	in vec3 frag_pos,
+	in vec2 texture_coords
 )
 {
 	vec3 view_direction = normalize(view_pos - frag_pos);
@@ -47,7 +48,7 @@ vec3 calc_specular_light(
 	float spec =
 		pow(max(dot(view_direction, reflect_direction), 0.0), material.shininess);
 
-	return light.specular * (spec * material.specular);
+	return light.specular * (spec * vec3(texture(material.specular, texture_coords)));
 }
 
 #endif
diff --git a/engine/src/lib.rs b/engine/src/lib.rs
index 30346ed..c4711f2 100644
--- a/engine/src/lib.rs
+++ b/engine/src/lib.rs
@@ -135,11 +135,13 @@ impl Engine
 
             let window_size = self.window.size().map_err(Error::GetWindowSizeFailed)?;
 
-            self.renderer.render(
-                self.objects.values(),
-                self.light_source.as_ref(),
-                &window_size,
-            );
+            self.renderer
+                .render(
+                    self.objects.values(),
+                    self.light_source.as_ref(),
+                    &window_size,
+                )
+                .map_err(Error::RenderingFailed)?;
 
             self.window
                 .swap_buffers()
@@ -234,4 +236,7 @@ pub enum Error
 
     #[error("Failed to get cursor position")]
     GetCursorPosFailed(#[source] glfw::Error),
+
+    #[error("Rendering failed")]
+    RenderingFailed(#[source] renderer::Error),
 }
diff --git a/engine/src/material.rs b/engine/src/material.rs
index 240d7e2..5af3282 100644
--- a/engine/src/material.rs
+++ b/engine/src/material.rs
@@ -1,32 +1,32 @@
-use crate::color::Color;
+use crate::texture::Id as TextureId;
 
 #[derive(Debug, Clone)]
 pub struct Material
 {
-    ambient: Color<f32>,
-    diffuse: Color<f32>,
-    specular: Color<f32>,
+    ambient_map: TextureId,
+    diffuse_map: TextureId,
+    specular_map: TextureId,
     shininess: f32,
 }
 
 impl Material
 {
     #[must_use]
-    pub fn ambient(&self) -> &Color<f32>
+    pub fn ambient_map(&self) -> &TextureId
     {
-        &self.ambient
+        &self.ambient_map
     }
 
     #[must_use]
-    pub fn diffuse(&self) -> &Color<f32>
+    pub fn diffuse_map(&self) -> &TextureId
     {
-        &self.diffuse
+        &self.diffuse_map
     }
 
     #[must_use]
-    pub fn specular(&self) -> &Color<f32>
+    pub fn specular_map(&self) -> &TextureId
     {
-        &self.specular
+        &self.specular_map
     }
 
     #[must_use]
@@ -40,9 +40,9 @@ impl Material
 #[derive(Debug, Clone)]
 pub struct Builder
 {
-    ambient: Color<f32>,
-    diffuse: Color<f32>,
-    specular: Color<f32>,
+    ambient_map: Option<TextureId>,
+    diffuse_map: Option<TextureId>,
+    specular_map: Option<TextureId>,
     shininess: f32,
 }
 
@@ -52,33 +52,33 @@ impl Builder
     pub fn new() -> Self
     {
         Self {
-            ambient: 0.2.into(),
-            diffuse: 0.5.into(),
-            specular: 1.0.into(),
+            ambient_map: None,
+            diffuse_map: None,
+            specular_map: None,
             shininess: 32.0,
         }
     }
 
     #[must_use]
-    pub fn ambient(mut self, ambient: Color<f32>) -> Self
+    pub fn ambient_map(mut self, ambient_map: TextureId) -> Self
     {
-        self.ambient = ambient;
+        self.ambient_map = Some(ambient_map);
 
         self
     }
 
     #[must_use]
-    pub fn diffuse(mut self, diffuse: Color<f32>) -> Self
+    pub fn diffuse_map(mut self, diffuse_map: TextureId) -> Self
     {
-        self.diffuse = diffuse;
+        self.diffuse_map = Some(diffuse_map);
 
         self
     }
 
     #[must_use]
-    pub fn specular(mut self, specular: Color<f32>) -> Self
+    pub fn specular_map(mut self, specular_map: TextureId) -> Self
     {
-        self.specular = specular;
+        self.specular_map = Some(specular_map);
 
         self
     }
@@ -92,13 +92,16 @@ impl Builder
     }
 
     /// Builds a new [`Material`].
+    ///
+    /// # Panics
+    /// Will panic if no ambient map, diffuse map or specular map is set.
     #[must_use]
     pub fn build(&self) -> Material
     {
         Material {
-            ambient: self.ambient.clone(),
-            diffuse: self.diffuse.clone(),
-            specular: self.specular.clone(),
+            ambient_map: self.ambient_map.unwrap(),
+            diffuse_map: self.diffuse_map.unwrap(),
+            specular_map: self.specular_map.unwrap(),
             shininess: self.shininess,
         }
     }
diff --git a/engine/src/object.rs b/engine/src/object.rs
index 6749124..4e143a0 100644
--- a/engine/src/object.rs
+++ b/engine/src/object.rs
@@ -1,8 +1,9 @@
+use std::collections::HashMap;
 use std::fs::read_to_string;
 use std::io::Error as IoError;
 use std::path::{Path, PathBuf};
 
-use crate::material::{Builder as MaterialBuilder, Material};
+use crate::material::Material;
 use crate::opengl::shader::{
     Error as ShaderError,
     Kind as ShaderKind,
@@ -11,7 +12,7 @@ use crate::opengl::shader::{
 };
 use crate::renderer::Renderable;
 use crate::shader_preprocessor::{Error as ShaderPreprocessorError, ShaderPreprocessor};
-use crate::texture::Texture;
+use crate::texture::{Id as TextureId, Texture};
 use crate::transform::Transform;
 use crate::vector::Vec3;
 use crate::vertex::Vertex;
@@ -19,8 +20,7 @@ use crate::vertex::Vertex;
 const SHADER_DIR: &str = "engine";
 
 const VERTEX_SHADER_FILE: &str = "vertex.glsl";
-const FRAG_SHADER_COLOR_FILE: &str = "fragment-color.glsl";
-const FRAG_SHADER_TEXTURE_FILE: &str = "fragment-texture.glsl";
+const FRAGMENT_SHADER_FILE: &str = "fragment.glsl";
 
 #[derive(Debug)]
 pub struct Object
@@ -28,7 +28,7 @@ pub struct Object
     id: Id,
     renderable: Renderable,
     transform: Transform,
-    texture: Option<Texture>,
+    textures: HashMap<TextureId, Texture>,
     material: Material,
 }
 
@@ -58,10 +58,9 @@ impl Object
         self.transform.set_scale(scaling);
     }
 
-    #[must_use]
-    pub fn texture(&self) -> Option<&Texture>
+    pub fn textures(&self) -> impl Iterator<Item = (&TextureId, &Texture)>
     {
-        self.texture.as_ref()
+        self.textures.iter()
     }
 
     #[must_use]
@@ -87,8 +86,8 @@ pub struct Builder
 {
     vertices: Vec<Vertex>,
     indices: Option<Vec<u32>>,
-    texture: Option<Texture>,
-    material: Material,
+    textures: HashMap<TextureId, Texture>,
+    material: Option<Material>,
 }
 
 impl Builder
@@ -100,8 +99,8 @@ impl Builder
         Self {
             vertices: Vec::new(),
             indices: None,
-            texture: None,
-            material: MaterialBuilder::new().build(),
+            textures: HashMap::new(),
+            material: None,
         }
     }
 
@@ -122,9 +121,19 @@ impl Builder
     }
 
     #[must_use]
-    pub fn texture(mut self, texture: Texture) -> Self
+    pub fn texture(mut self, id: TextureId, texture: Texture) -> Self
+    {
+        self.textures.insert(id, texture);
+
+        self
+    }
+
+    #[must_use]
+    pub fn textures<Textures>(mut self, textures: Textures) -> Self
+    where
+        Textures: IntoIterator<Item = (TextureId, Texture)>,
     {
-        self.texture = Some(texture);
+        self.textures.extend(textures);
 
         self
     }
@@ -132,7 +141,7 @@ impl Builder
     #[must_use]
     pub fn material(mut self, material: Material) -> Self
     {
-        self.material = material;
+        self.material = Some(material);
 
         self
     }
@@ -147,11 +156,7 @@ impl Builder
     {
         let vertex_shader_file = Path::new(SHADER_DIR).join(VERTEX_SHADER_FILE);
 
-        let fragment_shader_color_file =
-            Path::new(SHADER_DIR).join(FRAG_SHADER_COLOR_FILE);
-
-        let fragment_shader_texture_file =
-            Path::new(SHADER_DIR).join(FRAG_SHADER_TEXTURE_FILE);
+        let fragment_shader_file = Path::new(SHADER_DIR).join(FRAGMENT_SHADER_FILE);
 
         let vertex_shader_content =
             read_to_string(&vertex_shader_file).map_err(|err| {
@@ -161,17 +166,11 @@ impl Builder
                 }
             })?;
 
-        let fragment_shader_color_content = read_to_string(&fragment_shader_color_file)
-            .map_err(|err| Error::ReadShaderFailed {
-            source: err,
-            shader_file: fragment_shader_color_file.clone(),
-        })?;
-
-        let fragment_shader_texture_content =
-            read_to_string(&fragment_shader_texture_file).map_err(|err| {
+        let fragment_shader_content =
+            read_to_string(&fragment_shader_file).map_err(|err| {
                 Error::ReadShaderFailed {
                     source: err,
-                    shader_file: fragment_shader_texture_file.clone(),
+                    shader_file: fragment_shader_file.clone(),
                 }
             })?;
 
@@ -184,36 +183,20 @@ impl Builder
                 shader_file: vertex_shader_file,
             })?;
 
-        let frag_shader_color_content_preprocessed = shader_preprocessor
-            .preprocess(fragment_shader_color_content, &fragment_shader_color_file)
+        let frag_shader_content_preprocessed = shader_preprocessor
+            .preprocess(fragment_shader_content, &fragment_shader_file)
             .map_err(|err| Error::PreprocessShaderFailed {
                 source: err,
-                shader_file: fragment_shader_color_file,
-            })?;
-
-        let frag_shader_texture_content_preprocessed = shader_preprocessor
-            .preprocess(
-                fragment_shader_texture_content,
-                &fragment_shader_texture_file,
-            )
-            .map_err(|err| Error::PreprocessShaderFailed {
-                source: err,
-                shader_file: fragment_shader_texture_file,
+                shader_file: fragment_shader_file,
             })?;
 
         let vertex_shader =
             Self::create_shader(ShaderKind::Vertex, &vertex_shader_content_preprocessed)
                 .map_err(Error::CreateVertexShaderFailed)?;
 
-        let fragment_shader = Self::create_shader(
-            ShaderKind::Fragment,
-            if self.texture.is_some() {
-                &frag_shader_texture_content_preprocessed
-            } else {
-                &frag_shader_color_content_preprocessed
-            },
-        )
-        .map_err(Error::CreateFragmentShaderFailed)?;
+        let fragment_shader =
+            Self::create_shader(ShaderKind::Fragment, &frag_shader_content_preprocessed)
+                .map_err(Error::CreateFragmentShaderFailed)?;
 
         let shader_program = ShaderProgram::new();
 
@@ -233,8 +216,8 @@ impl Builder
             id,
             renderable,
             transform,
-            texture: self.texture,
-            material: self.material,
+            textures: self.textures,
+            material: self.material.ok_or(Error::NoMaterial)?,
         })
     }
 
@@ -285,6 +268,9 @@ pub enum Error
         source: ShaderPreprocessorError,
         shader_file: PathBuf,
     },
+
+    #[error("Object builder has no material")]
+    NoMaterial,
 }
 
 /// Object ID.
diff --git a/engine/src/opengl/shader.rs b/engine/src/opengl/shader.rs
index 9bed09b..224a9bc 100644
--- a/engine/src/opengl/shader.rs
+++ b/engine/src/opengl/shader.rs
@@ -153,7 +153,7 @@ impl Program
         Ok(())
     }
 
-    pub fn activate(&self, cb: impl FnOnce(CurrentlyBound<'_, Self>))
+    pub fn activate<Ret>(&self, cb: impl FnOnce(CurrentlyBound<'_, Self>) -> Ret) -> Ret
     {
         unsafe {
             gl::UseProgram(self.program);
@@ -162,7 +162,7 @@ impl Program
         // SAFETY: The shader program object is bound above
         let currently_bound = unsafe { CurrentlyBound::new() };
 
-        cb(currently_bound);
+        cb(currently_bound)
     }
 
     pub fn set_uniform_matrix_4fv(
@@ -205,6 +205,16 @@ impl Program
         }
     }
 
+    pub fn set_uniform_1i(&self, _: &CurrentlyBound<Self>, name: &CStr, num: i32)
+    {
+        let uniform_location =
+            unsafe { gl::GetUniformLocation(self.program, name.as_ptr().cast()) };
+
+        unsafe {
+            gl::Uniform1i(uniform_location, num);
+        }
+    }
+
     fn get_info_log(&self) -> String
     {
         let mut buf = vec![gl::types::GLchar::default(); 512];
diff --git a/engine/src/opengl/texture.rs b/engine/src/opengl/texture.rs
index 4186479..56eb118 100644
--- a/engine/src/opengl/texture.rs
+++ b/engine/src/opengl/texture.rs
@@ -1,6 +1,7 @@
 use std::ptr::null;
 
 use crate::opengl::currently_bound::CurrentlyBound;
+use crate::texture::Id;
 use crate::vector::Vec2;
 
 #[derive(Debug)]
@@ -234,3 +235,44 @@ impl PixelDataFormat
         }
     }
 }
+
+pub fn set_active_texture_unit(texture_unit: TextureUnit)
+{
+    unsafe {
+        gl::ActiveTexture(texture_unit.into_gl());
+    }
+}
+
+macro_rules! texture_unit_enum {
+    (cnt=$cnt: literal) => {
+        seq_macro::seq!(N in 0..$cnt {
+            #[derive(Debug, Clone, Copy)]
+            pub enum TextureUnit {
+                #(
+                    No~N,
+                )*
+            }
+
+            impl TextureUnit {
+                fn into_gl(self) -> gl::types::GLenum {
+                    match self {
+                        #(
+                            Self::No~N => gl::TEXTURE~N,
+                        )*
+                    }
+                }
+
+                pub fn from_texture_id(texture_id: Id) -> Option<Self> {
+                    match texture_id.into_inner() {
+                        #(
+                            N => Some(Self::No~N),
+                        )*
+                        _ => None
+                    }
+                }
+            }
+        });
+    };
+}
+
+texture_unit_enum!(cnt = 31);
diff --git a/engine/src/renderer/mod.rs b/engine/src/renderer/mod.rs
index 6fa692c..593b55f 100644
--- a/engine/src/renderer/mod.rs
+++ b/engine/src/renderer/mod.rs
@@ -18,6 +18,7 @@ use crate::opengl::currently_bound::CurrentlyBound;
 #[cfg(feature = "debug")]
 use crate::opengl::debug::{MessageSeverity, MessageSource, MessageType};
 use crate::opengl::shader::Program as ShaderProgram;
+use crate::opengl::texture::{set_active_texture_unit, TextureUnit};
 use crate::opengl::vertex_array::{PrimitiveKind, VertexArray};
 use crate::opengl::{clear_buffers, enable, BufferClearMask, Capability};
 use crate::projection::new_perspective;
@@ -69,7 +70,7 @@ impl Renderer
         objects: impl IntoIterator<Item = &'obj Object>,
         light_source: Option<&LightSource>,
         window_size: &WindowSize,
-    )
+    ) -> Result<(), Error>
     {
         clear_buffers(BufferClearMask::COLOR | BufferClearMask::DEPTH);
 
@@ -91,15 +92,22 @@ impl Renderer
                         &shader_program_curr_bound,
                     );
 
-                    if let Some(texture) = obj.texture() {
-                        texture.inner().bind(|_| {
-                            Self::draw_object(obj);
-                        });
-                    } else {
-                        Self::draw_object(obj);
+                    for (texture_id, texture) in obj.textures() {
+                        let texture_unit = TextureUnit::from_texture_id(*texture_id)
+                            .ok_or(Error::TextureIdIsInvalidTextureUnit)?;
+
+                        set_active_texture_unit(texture_unit);
+
+                        texture.inner().bind(|_| {});
                     }
-                });
+
+                    Self::draw_object(obj);
+
+                    Ok(())
+                })?;
         }
+
+        Ok(())
     }
 
     pub fn set_viewport(position: &Vec2<u32>, size: &WindowSize)
@@ -217,6 +225,9 @@ pub enum Error
 {
     #[error("Failed to get window size")]
     GetWindowSizeFailed(#[source] glfw::Error),
+
+    #[error("Texture ID is a invalid texture unit")]
+    TextureIdIsInvalidTextureUnit,
 }
 
 fn apply_transformation_matrices(
@@ -300,22 +311,25 @@ fn apply_light(
             .into(),
     );
 
-    obj.renderable().shader_program.set_uniform_vec_3fv(
+    #[allow(clippy::cast_possible_wrap)]
+    obj.renderable().shader_program.set_uniform_1i(
         shader_program_curr_bound,
         cstr!("material.ambient"),
-        &obj.material().ambient().clone().into(),
+        obj.material().ambient_map().into_inner() as i32,
     );
 
-    obj.renderable().shader_program.set_uniform_vec_3fv(
+    #[allow(clippy::cast_possible_wrap)]
+    obj.renderable().shader_program.set_uniform_1i(
         shader_program_curr_bound,
         cstr!("material.diffuse"),
-        &obj.material().diffuse().clone().into(),
+        obj.material().diffuse_map().into_inner() as i32,
     );
 
-    obj.renderable().shader_program.set_uniform_vec_3fv(
+    #[allow(clippy::cast_possible_wrap)]
+    obj.renderable().shader_program.set_uniform_1i(
         shader_program_curr_bound,
         cstr!("material.specular"),
-        &obj.material().specular().clone().into(),
+        obj.material().specular_map().into_inner() as i32,
     );
 
     obj.renderable().shader_program.set_uniform_1fv(
diff --git a/engine/src/texture.rs b/engine/src/texture.rs
index f32bc0a..f644b58 100644
--- a/engine/src/texture.rs
+++ b/engine/src/texture.rs
@@ -1,8 +1,9 @@
 use std::path::Path;
 
 use image::io::Reader as ImageReader;
-use image::{DynamicImage, ImageError};
+use image::{DynamicImage, EncodableLayout, ImageError, Rgb, RgbImage};
 
+use crate::color::Color;
 use crate::opengl::texture::{PixelDataFormat, Texture as InnerTexture};
 use crate::vector::Vec2;
 
@@ -67,6 +68,39 @@ impl Texture
         Ok(me)
     }
 
+    #[must_use]
+    pub fn new_from_color(dimensions: &Vec2<u32>, color: &Color<u8>) -> Self
+    {
+        let image = RgbImage::from_pixel(
+            dimensions.x,
+            dimensions.y,
+            Rgb([color.red, color.green, color.blue]),
+        );
+
+        let inner = InnerTexture::new();
+
+        inner.bind(|texture_curr_bound| {
+            InnerTexture::generate(
+                &texture_curr_bound,
+                dimensions,
+                image.as_bytes(),
+                PixelDataFormat::Rgb,
+            );
+        });
+
+        let me = Self {
+            inner,
+            pixel_data_format: PixelDataFormat::Rgb,
+            dimensions: dimensions.clone(),
+        };
+
+        me.set_wrap(Wrapping::Repeat);
+        me.set_magnifying_filter(Filtering::Linear);
+        me.set_minifying_filter(Filtering::Nearest);
+
+        me
+    }
+
     pub fn set_wrap(&self, wrapping: Wrapping)
     {
         self.inner.bind(|texture_curr_bound| {
@@ -126,3 +160,25 @@ pub enum Error
     #[error("Unsupported image data kind")]
     UnsupportedImageDataKind,
 }
+
+/// Texture ID.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Id
+{
+    id: u32,
+}
+
+impl Id
+{
+    /// Returns a new texture ID.
+    #[must_use]
+    pub fn new(id: u32) -> Self
+    {
+        Self { id }
+    }
+
+    pub(crate) fn into_inner(self) -> u32
+    {
+        self.id
+    }
+}