1 files changed, 59 insertions, 0 deletions
diff --git a/stockton-render/src/camera.rs b/stockton-render/src/camera.rs
new file mode 100644
index 0000000..dcc9d93
--- /dev/null
+++ b/stockton-render/src/camera.rs
@@ -0,0 +1,59 @@
+//! Things related to converting 3D world space to 2D screen space
+
+use legion::maybe_changed;
+use na::{look_at_lh, perspective_lh_zo};
+use stockton_types::{
+    components::{CameraSettings, CameraVPMatrix, Transform},
+    Vector3,
+};
+
+use stockton_skeleton::{draw_passes::DrawPass, Renderer};
+
+fn euler_to_direction(euler: &Vector3) -> Vector3 {
+    let pitch = euler.x;
+    let yaw = euler.y;
+    let _roll = euler.z; // TODO: Support camera roll
+
+    Vector3::new(
+        yaw.sin() * pitch.cos(),
+        pitch.sin(),
+        yaw.cos() * pitch.cos(),
+    )
+}
+
+#[system(for_each)]
+#[filter(maybe_changed::<Transform>() | maybe_changed::<CameraSettings>())]
+pub fn calc_vp_matrix<DP: DrawPass + 'static>(
+    transform: &Transform,
+    settings: &CameraSettings,
+    matrix: &mut CameraVPMatrix,
+    #[resource] renderer: &Renderer<DP>,
+) {
+    // Get look direction from euler angles
+    let direction = euler_to_direction(&transform.rotation);
+
+    // Converts world space to camera space
+    let view_matrix = look_at_lh(
+        &transform.position,
+        &(transform.position + direction),
+        &Vector3::new(0.0, 1.0, 0.0),
+    );
+
+    // Converts camera space to screen space
+    let projection_matrix = {
+        let mut temp = perspective_lh_zo(
+            renderer.get_aspect_ratio(),
+            settings.fov,
+            settings.near,
+            settings.far,
+        );
+
+        // Vulkan's co-ord system is different from OpenGLs
+        temp[(1, 1)] *= -1.0;
+
+        temp
+    };
+
+    // Chain them together into a single matrix
+    matrix.vp_matrix = projection_matrix * view_matrix;
+}