From 386aad9dac7c22cabb0f1bbba33d248c40bb0310 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Mon, 23 Oct 2023 22:23:25 +0200
Subject: feat(engine): add perspective

---
 engine/src/lib.rs          |  8 +++++++-
 engine/src/matrix.rs       |  9 ++++++++
 engine/src/projection.rs   | 21 +++++++++++++++++++
 engine/src/renderer/mod.rs | 51 +++++++++++++++++++++++++++++++++++++++++-----
 engine/vertex.glsl         |  6 ++++--
 5 files changed, 87 insertions(+), 8 deletions(-)
 create mode 100644 engine/src/projection.rs

(limited to 'engine')

diff --git a/engine/src/lib.rs b/engine/src/lib.rs
index dbbd407..ee93695 100644
--- a/engine/src/lib.rs
+++ b/engine/src/lib.rs
@@ -9,6 +9,7 @@ use crate::vector::Vec2;
 
 mod matrix;
 mod opengl;
+mod projection;
 mod renderer;
 mod transform;
 
@@ -93,7 +94,9 @@ impl Engine
         while !self.window.should_close() {
             func(self);
 
-            crate::renderer::render(self.objects.values());
+            let window_size = self.window.size().map_err(Error::GetWindowSizeFailed)?;
+
+            crate::renderer::render(self.objects.values(), &window_size);
 
             self.window
                 .swap_buffers()
@@ -123,4 +126,7 @@ pub enum Error
 
     #[error("Failed to update window")]
     UpdateWindowFailed(#[source] glfw::Error),
+
+    #[error("Failed to get window size")]
+    GetWindowSizeFailed(#[source] glfw::Error),
 }
diff --git a/engine/src/matrix.rs b/engine/src/matrix.rs
index 7e161f2..c060b59 100644
--- a/engine/src/matrix.rs
+++ b/engine/src/matrix.rs
@@ -10,6 +10,15 @@ pub struct Matrix<Value, const ROWS: usize, const COLUMNS: usize>
 
 impl<Value, const ROWS: usize, const COLUMNS: usize> Matrix<Value, ROWS, COLUMNS>
 {
+    pub fn new() -> Self
+    where
+        Value: Default + Copy,
+    {
+        Self {
+            items: [[Value::default(); ROWS]; COLUMNS],
+        }
+    }
+
     /// Sets the value at the specified cell.
     pub fn set_cell(&mut self, row: usize, column: usize, value: Value)
     {
diff --git a/engine/src/projection.rs b/engine/src/projection.rs
new file mode 100644
index 0000000..d5186ba
--- /dev/null
+++ b/engine/src/projection.rs
@@ -0,0 +1,21 @@
+use crate::matrix::Matrix;
+
+/// Creates a new perspective projection matrix.
+#[must_use]
+pub fn new_perspective(
+    fov_radians: f32,
+    aspect: f32,
+    far: f32,
+    near: f32,
+) -> Matrix<f32, 4, 4>
+{
+    let mut out = Matrix::new();
+
+    out.set_cell(0, 0, (1.0 / (fov_radians / 2.0).tan()) / aspect);
+    out.set_cell(1, 1, 1.0 / (fov_radians / 2.0).tan());
+    out.set_cell(2, 2, (near + far) / (near - far));
+    out.set_cell(2, 3, (2.0 * near * far) / (near - far));
+    out.set_cell(3, 2, -1.0);
+
+    out
+}
diff --git a/engine/src/renderer/mod.rs b/engine/src/renderer/mod.rs
index a02bbc2..d577054 100644
--- a/engine/src/renderer/mod.rs
+++ b/engine/src/renderer/mod.rs
@@ -4,6 +4,7 @@ use std::process::abort;
 use cstr::cstr;
 use glfw::WindowSize;
 
+use crate::matrix::Matrix;
 use crate::object::Object;
 use crate::opengl::buffer::{
     ArrayKind as ArrayBufferKind,
@@ -16,7 +17,8 @@ use crate::opengl::debug::{MessageSeverity, MessageSource, MessageType};
 use crate::opengl::shader::Program as ShaderProgram;
 use crate::opengl::vertex_array::{PrimitiveKind, VertexArray};
 use crate::opengl::{clear_buffers, BufferClearMask};
-use crate::vector::Vec2;
+use crate::projection::new_perspective;
+use crate::vector::{Vec2, Vec3};
 use crate::vertex::Vertex;
 
 pub fn initialize(window: &glfw::Window) -> Result<(), Error>
@@ -99,16 +101,25 @@ fn opengl_debug_message_cb(
     };
 }
 
-pub fn render<'obj>(objects: impl IntoIterator<Item = &'obj Object>)
+pub fn render<'obj>(
+    objects: impl IntoIterator<Item = &'obj Object>,
+    window_size: &WindowSize,
+)
 {
     clear_buffers(BufferClearMask::COLOR);
 
     for obj in objects {
         obj.renderable().shader_program.activate();
 
-        obj.renderable()
-            .shader_program
-            .set_uniform_matrix_4fv(cstr!("transform"), &obj.transform().as_matrix());
+        let mut view = Matrix::new_identity();
+
+        view.translate(&Vec3 {
+            x: 0.0,
+            y: 0.0,
+            z: -3.0,
+        });
+
+        apply_transformation_matrices(obj, &view, window_size);
 
         obj.renderable().vertex_arr.bind(|vert_arr_curr_bound| {
             if let Some(index_info) = &obj.renderable().index_info {
@@ -203,3 +214,33 @@ pub enum Error
     #[error("Failed to get window size")]
     GetWindowSizeFailed(#[source] glfw::Error),
 }
+
+fn apply_transformation_matrices(
+    object: &Object,
+    view: &Matrix<f32, 4, 4>,
+    window_size: &WindowSize,
+)
+{
+    object
+        .renderable()
+        .shader_program
+        .set_uniform_matrix_4fv(cstr!("model"), &object.transform().as_matrix());
+
+    object
+        .renderable()
+        .shader_program
+        .set_uniform_matrix_4fv(cstr!("view"), view);
+
+    #[allow(clippy::cast_precision_loss)]
+    let projection = new_perspective(
+        80.0f32.to_radians(),
+        window_size.width as f32 / window_size.height as f32,
+        0.1,
+        100.0,
+    );
+
+    object
+        .renderable()
+        .shader_program
+        .set_uniform_matrix_4fv(cstr!("projection"), &projection);
+}
diff --git a/engine/vertex.glsl b/engine/vertex.glsl
index db3d612..b0a2a13 100644
--- a/engine/vertex.glsl
+++ b/engine/vertex.glsl
@@ -4,11 +4,13 @@ layout (location = 1) in vec3 color;
 
 out vec3 in_frag_color;
 
-uniform mat4 transform;
+uniform mat4 model;
+uniform mat4 view;
+uniform mat4 projection;
 
 void main()
 {
-    gl_Position = transform * vec4(pos, 1.0);
+    gl_Position = projection * view * model * vec4(pos, 1.0);
 
 	in_frag_color = color;
 }
-- 
cgit v1.2.3-18-g5258