feat(engine): add translating & scaling objects

10 files changed, 176 insertions, 8 deletions

diff --git a/Cargo.lock b/Cargo.lock
index ed47841..7010e6c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -76,6 +76,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "cstr"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8aa998c33a6d3271e3678950a22134cd7dd27cef86dee1b611b5b14207d1d90b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+]
+
+[[package]]
 name = "either"
 version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -86,6 +96,7 @@ name = "engine"
 version = "0.1.0"
 dependencies = [
  "bitflags",
+ "cstr",
  "gl",
  "glfw",
  "thiserror",
diff --git a/engine/Cargo.toml b/engine/Cargo.toml
index ff52cce..023c711 100644
--- a/engine/Cargo.toml
+++ b/engine/Cargo.toml
@@ -11,4 +11,5 @@ glfw = { path = "../glfw" }
 thiserror = "1.0.49"
 gl = "0.14.0"
 bitflags = "2.4.0"
+cstr = "0.2.11"
 tracing = { version = "0.1.39", optional = true }
diff --git a/engine/src/lib.rs b/engine/src/lib.rs
index db6ab94..dbbd407 100644
--- a/engine/src/lib.rs
+++ b/engine/src/lib.rs
@@ -7,8 +7,10 @@ use glfw::{Window, WindowBuilder};
 use crate::object::{Id as ObjectId, Object};
 use crate::vector::Vec2;
 
+mod matrix;
 mod opengl;
 mod renderer;
+mod transform;
 
 pub mod color;
 pub mod object;
@@ -91,7 +93,7 @@ impl Engine
         while !self.window.should_close() {
             func(self);
 
-            crate::renderer::render(self.objects.values().map(Object::renderable));
+            crate::renderer::render(self.objects.values());
 
             self.window
                 .swap_buffers()
diff --git a/engine/src/matrix.rs b/engine/src/matrix.rs
new file mode 100644
index 0000000..7e161f2
--- /dev/null
+++ b/engine/src/matrix.rs
@@ -0,0 +1,65 @@
+use crate::vector::Vec3;
+
+#[derive(Debug, Clone)]
+#[repr(C)]
+pub struct Matrix<Value, const ROWS: usize, const COLUMNS: usize>
+{
+    /// Items must be layed out this way for it to work with OpenGL shaders.
+    items: [[Value; ROWS]; COLUMNS],
+}
+
+impl<Value, const ROWS: usize, const COLUMNS: usize> Matrix<Value, ROWS, COLUMNS>
+{
+    /// Sets the value at the specified cell.
+    pub fn set_cell(&mut self, row: usize, column: usize, value: Value)
+    {
+        self.items[column][row] = value;
+    }
+
+    #[must_use]
+    pub fn as_ptr(&self) -> *const Value
+    {
+        self.items[0].as_ptr()
+    }
+}
+
+impl<const ROWS_COLS: usize> Matrix<f32, ROWS_COLS, ROWS_COLS>
+{
+    /// Creates a new identity matrix.
+    #[must_use]
+    pub fn new_identity() -> Self
+    {
+        let mut index = 0;
+
+        let items = [(); ROWS_COLS].map(|()| {
+            let mut columns = [0.0; ROWS_COLS];
+
+            columns[index] = 1.0;
+
+            index += 1;
+
+            columns
+        });
+
+        Self { items }
+    }
+}
+
+impl Matrix<f32, 4, 4>
+{
+    pub fn translate(&mut self, translation: &Vec3<f32>)
+    {
+        self.set_cell(0, 3, translation.x);
+        self.set_cell(1, 3, translation.y);
+        self.set_cell(2, 3, translation.z);
+        self.set_cell(3, 3, 1.0);
+    }
+
+    pub fn scale(&mut self, scaling: &Vec3<f32>)
+    {
+        self.set_cell(0, 0, scaling.x);
+        self.set_cell(1, 1, scaling.y);
+        self.set_cell(2, 2, scaling.z);
+        self.set_cell(3, 3, 1.0);
+    }
+}
diff --git a/engine/src/object.rs b/engine/src/object.rs
index 11ba7e6..c3d82d0 100644
--- a/engine/src/object.rs
+++ b/engine/src/object.rs
@@ -5,6 +5,8 @@ use crate::opengl::shader::{
     Shader,
 };
 use crate::renderer::Renderable;
+use crate::transform::Transform;
+use crate::vector::Vec3;
 use crate::vertex::Vertex;
 
 #[derive(Debug)]
@@ -12,6 +14,7 @@ pub struct Object
 {
     id: Id,
     renderable: Renderable,
+    transform: Transform,
 }
 
 impl Object
@@ -53,7 +56,13 @@ impl Object
 
         let renderable = Renderable::new(shader_program, vertices);
 
-        Ok(Self { id, renderable })
+        let transform = Transform::new();
+
+        Ok(Self {
+            id,
+            renderable,
+            transform,
+        })
     }
 
     /// Returns the object ID.
@@ -63,10 +72,25 @@ impl Object
         self.id
     }
 
+    pub fn translate(&mut self, translation: Vec3<f32>)
+    {
+        self.transform.set_translation(translation);
+    }
+
+    pub fn scale(&mut self, scaling: Vec3<f32>)
+    {
+        self.transform.set_scaling(scaling);
+    }
+
     pub(crate) fn renderable(&self) -> &Renderable
     {
         &self.renderable
     }
+
+    pub(crate) fn transform(&self) -> &Transform
+    {
+        &self.transform
+    }
 }
 
 /// Object error
diff --git a/engine/src/opengl/shader.rs b/engine/src/opengl/shader.rs
index 0bbca77..603c790 100644
--- a/engine/src/opengl/shader.rs
+++ b/engine/src/opengl/shader.rs
@@ -1,6 +1,8 @@
 use std::ffi::CStr;
 use std::ptr::null_mut;
 
+use crate::matrix::Matrix;
+
 #[derive(Debug)]
 pub struct Shader
 {
@@ -156,6 +158,16 @@ impl Program
         }
     }
 
+    pub fn set_uniform_matrix_4fv(&self, name: &CStr, matrix: &Matrix<f32, 4, 4>)
+    {
+        let uniform_location =
+            unsafe { gl::GetUniformLocation(self.program, name.as_ptr().cast()) };
+
+        unsafe {
+            gl::UniformMatrix4fv(uniform_location, 1, gl::FALSE, matrix.as_ptr());
+        }
+    }
+
     fn get_info_log(&self) -> String
     {
         let mut buf = vec![gl::types::GLchar::default(); 512];
diff --git a/engine/src/renderer/mod.rs b/engine/src/renderer/mod.rs
index 8ca85e2..068b8f0 100644
--- a/engine/src/renderer/mod.rs
+++ b/engine/src/renderer/mod.rs
@@ -1,8 +1,10 @@
 use std::ffi::{c_void, CString};
 use std::process::abort;
 
+use cstr::cstr;
 use glfw::WindowSize;
 
+use crate::object::Object;
 #[cfg(feature = "debug")]
 use crate::opengl::debug::{MessageSeverity, MessageSource, MessageType};
 use crate::opengl::shader::Program as ShaderProgram;
@@ -92,14 +94,18 @@ fn opengl_debug_message_cb(
     };
 }
 
-pub fn render<'renderable>(renderables: impl IntoIterator<Item = &'renderable Renderable>)
+pub fn render<'obj>(objects: impl IntoIterator<Item = &'obj Object>)
 {
     clear_buffers(BufferClearMask::COLOR);
 
-    for renderable in renderables {
-        renderable.shader_program.activate();
+    for obj in objects {
+        obj.renderable().shader_program.activate();
 
-        renderable.vertex_arr.bind(|vert_arr_curr_bound| {
+        obj.renderable()
+            .shader_program
+            .set_uniform_matrix_4fv(cstr!("transform"), &obj.transform().as_matrix());
+
+        obj.renderable().vertex_arr.bind(|vert_arr_curr_bound| {
             VertexArray::draw(&vert_arr_curr_bound, PrimitiveKind::Triangles, 0, 3);
         });
     }
diff --git a/engine/src/transform.rs b/engine/src/transform.rs
new file mode 100644
index 0000000..9ce52ee
--- /dev/null
+++ b/engine/src/transform.rs
@@ -0,0 +1,45 @@
+use crate::matrix::Matrix;
+use crate::vector::Vec3;
+
+#[derive(Debug, Clone)]
+pub struct Transform
+{
+    translation: Vec3<f32>,
+    scaling: Vec3<f32>,
+}
+
+impl Transform
+{
+    pub fn new() -> Self
+    {
+        Self {
+            translation: Vec3::default(),
+            scaling: Vec3 {
+                x: 1.0,
+                y: 1.0,
+                z: 1.0,
+            },
+        }
+    }
+
+    pub fn set_translation(&mut self, translation: Vec3<f32>)
+    {
+        self.translation = translation;
+    }
+
+    pub fn set_scaling(&mut self, scaling: Vec3<f32>)
+    {
+        self.scaling = scaling;
+    }
+
+    pub fn as_matrix(&self) -> Matrix<f32, 4, 4>
+    {
+        let mut matrix = Matrix::new_identity();
+
+        matrix.translate(&self.translation);
+
+        matrix.scale(&self.scaling);
+
+        matrix
+    }
+}
diff --git a/engine/src/vector.rs b/engine/src/vector.rs
index ada64c4..c25a258 100644
--- a/engine/src/vector.rs
+++ b/engine/src/vector.rs
@@ -10,7 +10,7 @@ impl Vec2<u32>
     pub const ZERO: Self = Self { x: 0, y: 0 };
 }
 
-#[derive(Debug)]
+#[derive(Debug, Default, Clone)]
 #[repr(C)]
 pub struct Vec3<Value>
 {
diff --git a/engine/vertex.glsl b/engine/vertex.glsl
index 37d5677..db3d612 100644
--- a/engine/vertex.glsl
+++ b/engine/vertex.glsl
@@ -4,9 +4,11 @@ layout (location = 1) in vec3 color;
 
 out vec3 in_frag_color;
 
+uniform mat4 transform;
+
 void main()
 {
-    gl_Position = vec4(pos.x, pos.y, pos.z, 1.0);
+    gl_Position = transform * vec4(pos, 1.0);
 
 	in_frag_color = color;
 }