From 3d082505f7ca720bd34b1311a2ae7bca5e20a5f0 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Tue, 4 Mar 2025 20:15:43 +0000
Subject: Have Camera keep an array of frustum plane definitions

Based on code from https://ktstephano.github.io/rendering/stratusgfx/aabbs
---
 gfx/gl/camera.cpp | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'gfx/gl/camera.cpp')

diff --git a/gfx/gl/camera.cpp b/gfx/gl/camera.cpp
index f03e85b..9e165fa 100644
--- a/gfx/gl/camera.cpp
+++ b/gfx/gl/camera.cpp
@@ -29,6 +29,11 @@ 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);
+	});
 }
 
 Direction3D
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