4 files changed, 76 insertions, 32 deletions
diff --git a/gfx/camera.cpp b/gfx/camera.cpp
index 9e165fa..cc6a2dd 100644
--- a/gfx/camera.cpp
+++ b/gfx/camera.cpp
@@ -4,13 +4,16 @@
 #include <maths.h>
 #include <ray.h>
 
-Camera::Camera(GlobalPosition3D pos, Angle fov, Angle aspect, GlobalDistance zNear, GlobalDistance zFar) :
-	position {pos}, forward {::north}, up {::up}, near {zNear}, far {zFar}, view {},
-	projection {
-			glm::perspective(fov, aspect, static_cast<RelativeDistance>(zNear), static_cast<RelativeDistance>(zFar))},
-	viewProjection {}, inverseViewProjection {}
+Camera::Camera(GlobalPosition3D pos, Angle fov, Angle aspect, GlobalDistance near, GlobalDistance far) :
+	Camera {pos, near, far, glm::lookAt({}, ::north, ::up),
+			glm::perspective(fov, aspect, static_cast<RelativeDistance>(near), static_cast<RelativeDistance>(far))}
+{
+}
+
+Camera::Camera(GlobalPosition3D pos, GlobalDistance near, GlobalDistance far, const glm::mat4 & view,
+		const glm::mat4 & projection) :
+	Frustum {view, projection}, position {pos}, forward {::north}, up {::up}, near {near}, far {far}
 {
-	updateView();
 }
 
 Ray<GlobalPosition3D>
@@ -26,14 +29,7 @@ Camera::unProject(const ScreenRelCoord & mouse) const
 void
 Camera::updateView()
 {
-	view = glm::lookAt({}, forward, up);
-	viewProjection = projection * view;
-	inverseViewProjection = glm::inverse(viewProjection);
-	static constexpr auto PLANES = std::array {0, 1, 2} * std::array {1.F, -1.F};
-	std::ranges::transform(PLANES, frustumPlanes.begin(), [vpt = glm::transpose(viewProjection)](const auto & idxs) {
-		const auto [idx, sgn] = idxs;
-		return vpt[3] + (vpt[idx] * sgn);
-	});
+	Frustum::updateView(glm::lookAt({}, forward, up));
 }
 
 Direction3D
diff --git a/gfx/camera.h b/gfx/camera.h
index d4fe6de..a52ec8b 100644
--- a/gfx/camera.h
+++ b/gfx/camera.h
@@ -1,19 +1,14 @@
 #pragma once
 
 #include "config/types.h"
+#include "frustum.h"
 #include <glm/glm.hpp>
 #include <maths.h>
 #include <ray.h>
 
-class Camera {
+class Camera : public Frustum {
 public:
-	Camera(GlobalPosition3D, Angle fov, Angle aspect, GlobalDistance zNear, GlobalDistance zFar);
-
-	[[nodiscard]] glm::mat4
-	getViewProjection() const
-	{
-		return viewProjection;
-	}
+	Camera(GlobalPosition3D position, Angle fov, Angle aspect, GlobalDistance near, GlobalDistance far);
 
 	[[nodiscard]] Ray<GlobalPosition3D> unProject(const ScreenRelCoord &) const;
 
@@ -70,25 +65,17 @@ public:
 		return position;
 	}
 
-	[[nodiscard]] auto &
-	getFrustumPlanes() const
-	{
-		return frustumPlanes;
-	}
-
 	[[nodiscard]] std::array<GlobalPosition4D, 4> extentsAtDist(GlobalDistance) const;
 
 	[[nodiscard]] static Direction3D upFromForward(const Direction3D & forward);
 
 private:
+	Camera(GlobalPosition3D position, GlobalDistance near, GlobalDistance far, const glm::mat4 & view,
+			const glm::mat4 & projection);
 	void updateView();
 
 	GlobalPosition3D position;
 	Direction3D forward;
 	Direction3D up;
-
 	GlobalDistance near, far;
-	glm::mat4 view, projection;
-	glm::mat4 viewProjection, inverseViewProjection;
-	std::array<glm::vec4, 6> frustumPlanes;
 };
diff --git a/gfx/frustum.cpp b/gfx/frustum.cpp
new file mode 100644
index 0000000..9e046f6
--- /dev/null
+++ b/gfx/frustum.cpp
@@ -0,0 +1,30 @@
+#include "frustum.h"
+#include <algorithm>
+#include <collections.h>
+#include <glm/ext/matrix_transform.hpp>
+
+static constexpr auto PLANES = std::array {0, 1, 2} * std::array {1.F, -1.F};
+
+Frustum::Frustum(const glm::mat4 & view, const glm::mat4 & projection) :
+	view {view}, projection {projection}, viewProjection {}, inverseViewProjection {}, planes {}
+{
+	updateCache();
+}
+
+void
+Frustum::updateView(const glm::mat4 & newView)
+{
+	view = newView;
+	updateCache();
+}
+
+void
+Frustum::updateCache()
+{
+	viewProjection = projection * view;
+	inverseViewProjection = glm::inverse(viewProjection);
+	std::ranges::transform(PLANES, planes.begin(), [vpt = glm::transpose(viewProjection)](const auto & idxs) {
+		const auto [idx, sgn] = idxs;
+		return vpt[3] + (vpt[idx] * sgn);
+	});
+}
diff --git a/gfx/frustum.h b/gfx/frustum.h
new file mode 100644
index 0000000..25dcc18
--- /dev/null
+++ b/gfx/frustum.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include <array>
+#include <glm/mat4x4.hpp>
+
+class Frustum {
+public:
+	Frustum(const glm::mat4 & view, const glm::mat4 & projection);
+
+	[[nodiscard]] auto &
+	getFrustumPlanes() const
+	{
+		return planes;
+	}
+
+	[[nodiscard]] auto &
+	getViewProjection() const
+	{
+		return viewProjection;
+	}
+
+	void updateView(const glm::mat4 & view);
+
+protected:
+	static constexpr size_t FACES = 6;
+	void updateCache();
+
+	glm::mat4 view, projection;
+	glm::mat4 viewProjection, inverseViewProjection;
+	std::array<glm::vec4, FACES> planes;
+};