From 9a43f9e749f9f51cb37dabd9c1d33f2ee9441b2f Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Thu, 17 Oct 2024 18:26:24 +0100
Subject: Re-express viewProjections calculations as a fold expression

---
 gfx/gl/shadowStenciller.cpp | 10 +++++-----
 gfx/gl/shadowStenciller.h   |  4 +++-
 2 files changed, 8 insertions(+), 6 deletions(-)

(limited to 'gfx/gl')

diff --git a/gfx/gl/shadowStenciller.cpp b/gfx/gl/shadowStenciller.cpp
index 55ad8e1..89b61cc 100644
--- a/gfx/gl/shadowStenciller.cpp
+++ b/gfx/gl/shadowStenciller.cpp
@@ -10,8 +10,6 @@
 #include "maths.h"
 #include <stdexcept>
 
-template<typename T> constexpr T STENCIL_ANGLES = 8;
-
 ShadowStenciller::ShadowStenciller() :
 	shadowCaster {shadowStencil_vs, shadowStencil_gs, shadowStencil_fs}, viewProjections {}
 {
@@ -24,9 +22,11 @@ ShadowStenciller::ShadowStenciller() :
 void
 ShadowStenciller::setLightDirection(const LightDirection & lightDir)
 {
-	viewProjections = std::array<float, 8> {0, 1, 2, 3, 4, 5, 6, 7} * [&lightDir](const auto & ep) {
-		return rotate_pitch(half_pi - lightDir.position().y) * rotate_yaw((ep * quarter_pi) - lightDir.position().x);
-	};
+	viewProjections = [&lightDir]<GLint... Ep>(std::integer_sequence<GLint, Ep...>) {
+		constexpr float STEP = two_pi / STENCIL_ANGLES<decltype(two_pi)>;
+		return std::array {
+				rotate_pitch(half_pi - lightDir.position().y) * rotate_yaw((Ep * STEP) - lightDir.position().x)...};
+	}(std::make_integer_sequence<GLint, STENCIL_ANGLES<GLint>>());
 }
 
 glTexture
diff --git a/gfx/gl/shadowStenciller.h b/gfx/gl/shadowStenciller.h
index 03efced..ac83eb1 100644
--- a/gfx/gl/shadowStenciller.h
+++ b/gfx/gl/shadowStenciller.h
@@ -9,6 +9,8 @@ class LightDirection;
 
 class ShadowStenciller {
 public:
+	template<typename T> static constexpr T STENCIL_ANGLES = 8;
+
 	ShadowStenciller();
 
 	[[nodiscard]]
@@ -21,5 +23,5 @@ private:
 	Program shadowCaster;
 	Program::RequiredUniformLocation viewProjectionLoc {shadowCaster, "viewProjection"};
 
-	std::array<glm::mat4, 8> viewProjections;
+	std::array<glm::mat4, STENCIL_ANGLES<size_t>> viewProjections;
 };
-- 
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