Wip frustum code port

src/camera.rs

@@ -1,7 +1,11 @@
 use glam::{Mat4, Vec3};
-use shipyard::{Component, ViewMut, View, IntoIter, Workload, IntoWorkload};
+use shipyard::{Component, Workload, IntoWorkload};
 use std::f32::consts::PI;
-use crate::{transform::Transform, events::WindowResizedEvent};
+
+mod matrices;
+mod frustum;
+
+use matrices::update_matrices;
 
 #[derive(Component)]
 pub struct Camera {
@@ -29,36 +33,6 @@ impl Default for Camera {
 
 pub fn compute_cameras() -> Workload {
   (
-    update_perspective_matrix,
+    update_matrices,
-    update_view_matrix,
   ).into_workload()
 }
-
-fn update_view_matrix(
-  mut vm_camera: ViewMut<Camera>,
-  v_transform: View<Transform>
-) {
-  for (camera, transform) in (&mut vm_camera, v_transform.inserted_or_modified()).iter() {
-    let (_, rotation, translation) = transform.0.to_scale_rotation_translation();
-    let direction = rotation * Vec3::NEG_Z;
-    camera.view_matrix = Mat4::look_to_rh(translation, direction, camera.up);
-  }
-}
-
-fn update_perspective_matrix(
-  mut vm_camera: ViewMut<Camera>,
-  resize: View<WindowResizedEvent>,
-) {
-  //TODO update on launch
-  let Some(&size) = resize.iter().next() else {
-    return
-  };
-  for camera in (&mut vm_camera).iter() {
-    camera.perspective_matrix = Mat4::perspective_rh_gl(
-      camera.fov, 
-      size.0.x as f32 / size.0.y as f32, 
-      camera.z_near,
-      camera.z_far, 
-    )
-  }
-}

src/camera/frustum.rs

@@ -0,0 +1,66 @@
+// basically ported from c++
+// - used as a reference:
+//   [ https://github.com/Beastwick18/gltest/blob/main/src/renderer/Frustum.cpp ]
+//   - original code: 
+//     [ https://gist.github.com/podgorskiy/e698d18879588ada9014768e3e82a644 ]
+//     - which uses cube vs frustum intersection code from:
+//       [ http://iquilezles.org/www/articles/frustumcorrect/frustumcorrect.htm ]
+// three layers of stolen code, yay!
+
+use glam::{Vec3, Vec4, Vec4Swizzles};
+
+use super::Camera;
+
+
+#[repr(usize)]
+enum FrustumPlane {
+  Left,
+  Right,
+  Bottom,
+  Top,
+  Near,
+  Far,
+}
+const PLANE_COUNT: usize = 6;
+const PLANE_COMBINATIONS: usize = PLANE_COUNT * (PLANE_COUNT - 1) / 2;
+
+struct Frustum {
+  planes: [Vec4; PLANE_COUNT],
+  crosses: [Vec3; PLANE_COMBINATIONS],
+}
+impl Frustum {
+  pub fn compute(camera: &Camera) -> Self {
+    //compute transposed view-projection matrix
+    let mat = (camera.perspective_matrix * camera.view_matrix).transpose();
+
+    // compute planes
+    let mut planes = [Vec4::default(); PLANE_COUNT];
+    planes[FrustumPlane::Left   as usize] = mat.w_axis + mat.x_axis;
+    planes[FrustumPlane::Right  as usize] = mat.w_axis - mat.x_axis;
+    planes[FrustumPlane::Bottom as usize] = mat.w_axis + mat.y_axis;
+    planes[FrustumPlane::Top    as usize] = mat.w_axis - mat.y_axis;
+    planes[FrustumPlane::Near   as usize] = mat.w_axis + mat.z_axis;
+    planes[FrustumPlane::Far    as usize] = mat.w_axis - mat.z_axis;
+
+    //compute crosses
+    let crosses = [
+      planes[FrustumPlane::Left as usize].xyz().cross(planes[FrustumPlane::Right as usize].xyz()),
+      planes[FrustumPlane::Left as usize].xyz().cross(planes[FrustumPlane::Bottom as usize].xyz()),
+      planes[FrustumPlane::Left as usize].xyz().cross(planes[FrustumPlane::Top as usize].xyz()),
+      planes[FrustumPlane::Left as usize].xyz().cross(planes[FrustumPlane::Near as usize].xyz()),
+      planes[FrustumPlane::Left as usize].xyz().cross(planes[FrustumPlane::Far as usize].xyz()),
+      planes[FrustumPlane::Right as usize].xyz().cross(planes[FrustumPlane::Bottom as usize].xyz()),
+      planes[FrustumPlane::Right as usize].xyz().cross(planes[FrustumPlane::Top as usize].xyz()),
+      planes[FrustumPlane::Right as usize].xyz().cross(planes[FrustumPlane::Near as usize].xyz()),
+      planes[FrustumPlane::Right as usize].xyz().cross(planes[FrustumPlane::Far as usize].xyz()),
+      planes[FrustumPlane::Bottom as usize].xyz().cross(planes[FrustumPlane::Top as usize].xyz()),
+      planes[FrustumPlane::Bottom as usize].xyz().cross(planes[FrustumPlane::Near as usize].xyz()),
+      planes[FrustumPlane::Bottom as usize].xyz().cross(planes[FrustumPlane::Far as usize].xyz()),
+      planes[FrustumPlane::Top as usize].xyz().cross(planes[FrustumPlane::Near as usize].xyz()),
+      planes[FrustumPlane::Top as usize].xyz().cross(planes[FrustumPlane::Far as usize].xyz()),
+      planes[FrustumPlane::Near as usize].xyz().cross(planes[FrustumPlane::Far as usize].xyz()),
+    ];
+    
+    Self { planes, crosses }
+  }
+}

src/camera/matrices.rs

@@ -0,0 +1,42 @@
+use glam::{Vec3, Mat4};
+use shipyard::{ViewMut, View, IntoIter, Workload, IntoWorkload};
+use crate::{transform::Transform, events::WindowResizedEvent};
+use super::Camera;
+
+//maybe parallelize these two?
+
+fn update_view_matrix(
+  mut vm_camera: ViewMut<Camera>,
+  v_transform: View<Transform>
+) {
+  for (camera, transform) in (&mut vm_camera, v_transform.inserted_or_modified()).iter() {
+    let (_, rotation, translation) = transform.0.to_scale_rotation_translation();
+    let direction = rotation * Vec3::NEG_Z;
+    camera.view_matrix = Mat4::look_to_rh(translation, direction, camera.up);
+  }
+}
+
+fn update_perspective_matrix(
+  mut vm_camera: ViewMut<Camera>,
+  resize: View<WindowResizedEvent>,
+) {
+  //TODO update on launch
+  let Some(&size) = resize.iter().next() else {
+    return
+  };
+  for camera in (&mut vm_camera).iter() {
+    camera.perspective_matrix = Mat4::perspective_rh_gl(
+      camera.fov, 
+      size.0.x as f32 / size.0.y as f32, 
+      camera.z_near,
+      camera.z_far, 
+    )
+  }
+}
+
+pub fn update_matrices() -> Workload {
+  (
+    update_view_matrix, 
+    update_perspective_matrix,
+  ).into_workload()
+}