From dd452f3e9238be954c3ecd325ed11e97a50ec1c3 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 19 Aug 2024 23:26:32 +0100
Subject: Persist a single ShadowStenciller within ShadowMapper

---
 gfx/gl/shadowMapper.cpp     | 2 +-
 gfx/gl/shadowMapper.h       | 2 ++
 gfx/gl/shadowStenciller.cpp | 9 +++++++--
 gfx/gl/shadowStenciller.h   | 6 ++++--
 4 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/gfx/gl/shadowMapper.cpp b/gfx/gl/shadowMapper.cpp
index ff0634e..d9dd24f 100644
--- a/gfx/gl/shadowMapper.cpp
+++ b/gfx/gl/shadowMapper.cpp
@@ -80,7 +80,7 @@ ShadowMapper::update(const SceneProvider & scene, const Direction3D & dir, const
 	glCullFace(GL_FRONT);
 	glEnable(GL_DEPTH_TEST);
 
-	ShadowStenciller shadowStenciller {dir, up};
+	shadowStenciller.setLightDirection(dir, up);
 	for (const auto & [id, asset] : gameState->assets) {
 		if (const auto r = std::dynamic_pointer_cast<const Renderable>(asset)) {
 			r->updateStencil(shadowStenciller);
diff --git a/gfx/gl/shadowMapper.h b/gfx/gl/shadowMapper.h
index 73dadd0..280a0cd 100644
--- a/gfx/gl/shadowMapper.h
+++ b/gfx/gl/shadowMapper.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "config/types.h"
+#include "gfx/gl/shadowStenciller.h"
 #include "lib/glArrays.h"
 #include "program.h"
 #include <gfx/models/texture.h>
@@ -61,4 +62,5 @@ private:
 	glFrameBuffer depthMapFBO;
 	glTexture depthMap;
 	TextureAbsCoord size;
+	mutable ShadowStenciller shadowStenciller;
 };
diff --git a/gfx/gl/shadowStenciller.cpp b/gfx/gl/shadowStenciller.cpp
index fc3d77c..ac63b4e 100644
--- a/gfx/gl/shadowStenciller.cpp
+++ b/gfx/gl/shadowStenciller.cpp
@@ -7,8 +7,7 @@
 #include "gl_traits.h"
 #include <stdexcept>
 
-ShadowStenciller::ShadowStenciller(const Direction3D & lightDir, const Direction3D & lightDirUp) :
-	shadowCaster {shadowStencil_vs, shadowStencil_fs}, lightDirMat {glm::lookAt(-lightDir, {}, lightDirUp)}
+ShadowStenciller::ShadowStenciller() : shadowCaster {shadowStencil_vs, shadowStencil_fs}
 {
 	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
 	glDrawBuffer(GL_NONE);
@@ -16,6 +15,12 @@ ShadowStenciller::ShadowStenciller(const Direction3D & lightDir, const Direction
 	glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
+void
+ShadowStenciller::setLightDirection(const Direction3D & lightDir, const Direction3D & lightDirUp)
+{
+	lightDirMat = glm::lookAt(-lightDir, {}, lightDirUp);
+}
+
 glTexture
 ShadowStenciller::createStencilTexture(GLsizei width, GLsizei height)
 {
diff --git a/gfx/gl/shadowStenciller.h b/gfx/gl/shadowStenciller.h
index 87dc044..009285c 100644
--- a/gfx/gl/shadowStenciller.h
+++ b/gfx/gl/shadowStenciller.h
@@ -7,15 +7,17 @@
 
 class ShadowStenciller {
 public:
-	ShadowStenciller(const Direction3D & lightDir, const Direction3D & lightDirUp);
+	ShadowStenciller();
 
 	[[nodiscard]]
 	static glTexture createStencilTexture(GLsizei width, GLsizei height);
+	void setLightDirection(const Direction3D & lightDir, const Direction3D & lightDirUp);
 	void renderStencil(const glTexture &, const MeshBase &, const Texture::AnyPtr texture) const;
 
 private:
 	glFrameBuffer fbo;
 	Program shadowCaster;
-	glm::mat4 lightDirMat;
 	Program::UniformLocation viewProjectionLoc {shadowCaster, "viewProjection"};
+
+	glm::mat4 lightDirMat {};
 };
-- 
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