From 812d574082b951a6b60db5f61373bb5a87a01cbe Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Thu, 2 Apr 2026 16:35:34 +0200
Subject: fix(engine): make orthographic camera projection actually usable

---
 engine/src/projection.rs     | 61 ++++++++++++++++++++++++++++----------------
 engine/src/shader/default.rs | 17 ++++++------
 2 files changed, 47 insertions(+), 31 deletions(-)

(limited to 'engine')

diff --git a/engine/src/projection.rs b/engine/src/projection.rs
index 29636e7..46df6d4 100644
--- a/engine/src/projection.rs
+++ b/engine/src/projection.rs
@@ -1,7 +1,7 @@
 use crate::builder;
-use crate::data_types::dimens::Dimens3;
+use crate::data_types::dimens::Dimens;
 use crate::matrix::Matrix;
-use crate::vector::Vec3;
+use crate::vector::Vec2;
 
 #[derive(Debug, Clone)]
 #[non_exhaustive]
@@ -25,7 +25,7 @@ impl Perspective
     /// Creates a perspective projection matrix using right-handed coordinates.
     #[inline]
     pub fn to_matrix_rh(&self, aspect: f32, clip_volume: ClipVolume)
-        -> Matrix<f32, 4, 4>
+    -> Matrix<f32, 4, 4>
     {
         let mut out = Matrix::new();
 
@@ -55,13 +55,23 @@ impl Default for Perspective
     }
 }
 
+#[derive(Debug, Clone)]
+pub enum OrthographicSize
+{
+    FixedSize(Dimens<f32>),
+    WindowSize,
+}
+
 builder! {
 #[builder(name = OrthographicBuilder, derives=(Debug, Clone))]
-#[derive(Debug, Clone, PartialEq, PartialOrd)]
+#[derive(Debug, Clone)]
 #[non_exhaustive]
 pub struct Orthographic
 {
-    pub size: Dimens3<f32>,
+    pub near: f32,
+    pub far: f32,
+    pub viewport_origin: Vec2<f32>,
+    pub size: OrthographicSize,
 }
 }
 
@@ -75,18 +85,28 @@ impl Orthographic
     /// Creates a orthographic projection matrix using right-handed coordinates.
     pub fn to_matrix_rh(
         &self,
-        center_pos: &Vec3<f32>,
+        window_size: Dimens<f32>,
         clip_volume: ClipVolume,
     ) -> Matrix<f32, 4, 4>
     {
         let mut result = Matrix::<f32, 4, 4>::new();
 
-        let left = center_pos.x - (self.size.width / 2.0);
-        let right = center_pos.x + (self.size.width / 2.0);
-        let bottom = center_pos.y - (self.size.height / 2.0);
-        let top = center_pos.y + (self.size.height / 2.0);
-        let near = center_pos.z - (self.size.depth / 2.0);
-        let far = center_pos.z + (self.size.depth / 2.0);
+        let size = match self.size {
+            OrthographicSize::FixedSize(fixed_size) => fixed_size,
+            OrthographicSize::WindowSize => window_size,
+        };
+
+        let origin_x = size.width * self.viewport_origin.x;
+        let origin_y = size.height * self.viewport_origin.y;
+
+        let left = -origin_x;
+        let right = size.width - origin_x;
+
+        let bottom = -origin_y;
+        let top = size.height - origin_y;
+
+        let near = self.near;
+        let far = self.far;
 
         match clip_volume {
             ClipVolume::NegOneToOne => {
@@ -108,13 +128,7 @@ impl Default for Orthographic
 {
     fn default() -> Self
     {
-        Self {
-            size: Dimens3 {
-                width: 10.0,
-                height: 7.0,
-                depth: 10.0,
-            },
-        }
+        Self::builder().build()
     }
 }
 
@@ -122,9 +136,12 @@ impl Default for OrthographicBuilder
 {
     fn default() -> Self
     {
-        let orthographic = Orthographic::default();
-
-        OrthographicBuilder { size: orthographic.size }
+        Self {
+            near: 0.0,
+            far: 1000.0,
+            viewport_origin: Vec2 { x: 0.5, y: 0.5 },
+            size: OrthographicSize::WindowSize,
+        }
     }
 }
 
diff --git a/engine/src/shader/default.rs b/engine/src/shader/default.rs
index bc8202c..8690eb9 100644
--- a/engine/src/shader/default.rs
+++ b/engine/src/shader/default.rs
@@ -148,12 +148,7 @@ pub fn enqueue_set_shader_bindings(
             ),
             (
                 model_3d_shader_cursor.field("projection"),
-                create_projection_matrix(
-                    &camera,
-                    &camera_world_pos.position,
-                    window.inner_size(),
-                )
-                .into(),
+                create_projection_matrix(&camera, window.inner_size()).into(),
             ),
             (
                 lighting_shader_cursor.field("view_pos"),
@@ -340,7 +335,6 @@ fn create_view_matrix(camera: &Camera, camera_world_pos: &Vec3<f32>)
 
 fn create_projection_matrix(
     camera: &Camera,
-    camera_world_pos: &Vec3<f32>,
     window_size: &Dimens<u32>,
 ) -> Matrix<f32, 4, 4>
 {
@@ -349,8 +343,13 @@ fn create_projection_matrix(
             window_size.width as f32 / window_size.height as f32,
             ProjectionClipVolume::NegOneToOne,
         ),
-        Projection::Orthographic(orthographic_proj) => orthographic_proj
-            .to_matrix_rh(camera_world_pos, ProjectionClipVolume::NegOneToOne),
+        Projection::Orthographic(orthographic_proj) => orthographic_proj.to_matrix_rh(
+            Dimens {
+                width: window_size.width as f32,
+                height: window_size.height as f32,
+            },
+            ProjectionClipVolume::NegOneToOne,
+        ),
     }
 }
 
-- 
cgit v1.2.3-18-g5258