From 66047d123769245e3b5cb8bbe748aefb13db16d4 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Wed, 28 Dec 2022 19:36:00 +0000
Subject: Generate 4 bands of shadow maps

---
 gfx/gl/shaders/directionalLight.fs |  2 +-
 gfx/gl/shadowMapper.cpp            | 28 ++++++++++++++++++++--------
 gfx/gl/shadowMapper.h              |  3 ++-
 3 files changed, 23 insertions(+), 10 deletions(-)

(limited to 'gfx')

diff --git a/gfx/gl/shaders/directionalLight.fs b/gfx/gl/shaders/directionalLight.fs
index fa1e38d..ca10ef5 100644
--- a/gfx/gl/shaders/directionalLight.fs
+++ b/gfx/gl/shaders/directionalLight.fs
@@ -1,7 +1,7 @@
 #version 330 core
 #extension GL_ARB_shading_language_420pack : enable
 
-const int MAX_MAPS = 3;
+const int MAX_MAPS = 4;
 
 out vec3 FragColor;
 
diff --git a/gfx/gl/shadowMapper.cpp b/gfx/gl/shadowMapper.cpp
index b41a53b..f1beb82 100644
--- a/gfx/gl/shadowMapper.cpp
+++ b/gfx/gl/shadowMapper.cpp
@@ -33,17 +33,29 @@ ShadowMapper::ShadowMapper(const glm::ivec2 & s) : size {s}
 	glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
-constexpr std::array<glm::ivec4, 1> viewports {{
-		{31, 31, 0, 0},
+constexpr std::array<glm::ivec4, ShadowMapper::SHADOW_BANDS> viewports {{
+		{31, 31, 1, 1},
+		{1, 31, 1, 1},
+		{31, 1, 1, 1},
+		{1, 1, 1, 1},
 }};
-constexpr std::array<glm::vec4, 1> shadowMapRegions {
-		{{0.5F, 0.5F, 0.5F, 0.5F}},
+constexpr std::array<glm::vec4, ShadowMapper::SHADOW_BANDS> shadowMapRegions {{
+		{0.25F, 0.25F, 0.25F, 0.25F},
+		{0.25F, 0.25F, 0.75F, 0.25F},
+		{0.25F, 0.25F, 0.25F, 0.75F},
+		{0.25F, 0.25F, 0.75F, 0.75F},
+}};
+constexpr std::array<float, ShadowMapper::SHADOW_BANDS + 1> shadowBands {
+		1.F,
+		250.F,
+		750.F,
+		2500.F,
+		10000.F,
 };
-constexpr std::array shadowBands {1.F, 1000.F};
 static_assert(viewports.size() == shadowMapRegions.size());
 static_assert(shadowBands.size() == shadowMapRegions.size() + 1);
 
-ShadowMapper::Definitions<1>
+ShadowMapper::Definitions<ShadowMapper::SHADOW_BANDS>
 ShadowMapper::update(const SceneProvider & scene, const glm::vec3 & dir, const Camera & camera) const
 {
 	glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
@@ -61,8 +73,8 @@ ShadowMapper::update(const SceneProvider & scene, const glm::vec3 & dir, const C
 	for (auto & e : viewExtents) {
 		e = lightView * glm::vec4(e, 1);
 	}
-	Definitions<1> out;
-	for (std::size_t band = 0; band < viewports.size(); ++band) {
+	Definitions<SHADOW_BANDS> out;
+	for (std::size_t band = 0; band < SHADOW_BANDS; ++band) {
 		const auto extents_minmax = [extents = viewExtents.subspan(band * 4, 8)](auto && comp) {
 			const auto mm = std::minmax_element(extents.begin(), extents.end(), comp);
 			return std::make_pair(comp.get(*mm.first), comp.get(*mm.second));
diff --git a/gfx/gl/shadowMapper.h b/gfx/gl/shadowMapper.h
index d5f091e..7065ffe 100644
--- a/gfx/gl/shadowMapper.h
+++ b/gfx/gl/shadowMapper.h
@@ -11,11 +11,12 @@ class ShadowMapper {
 public:
 	ShadowMapper(const glm::ivec2 & size);
 
+	static constexpr std::size_t SHADOW_BANDS {4};
 	template<std::size_t S> struct Definitions {
 		std::array<glm::mat4x4, S> projections;
 		std::array<glm::vec4, S> regions;
 	};
-	Definitions<1> update(const SceneProvider &, const glm::vec3 & direction, const Camera &) const;
+	Definitions<SHADOW_BANDS> update(const SceneProvider &, const glm::vec3 & direction, const Camera &) const;
 
 	class FixedPoint : public Program {
 	public:
-- 
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