From 0cf44f532a3d8c83e0e24858cd5303d5daf84b6d Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 12 Dec 2020 20:49:50 +0300
Subject: [PATCH] Deferred renderer: add proper frustum culling

---
 libs/gfx/source/renderer/deferred.cpp | 33 ++++++++-------------------
 1 file changed, 9 insertions(+), 24 deletions(-)

diff --git a/libs/gfx/source/renderer/deferred.cpp b/libs/gfx/source/renderer/deferred.cpp
index 02247c6e..f2511c4d 100644
--- a/libs/gfx/source/renderer/deferred.cpp
+++ b/libs/gfx/source/renderer/deferred.cpp
@@ -20,6 +20,9 @@
 #include <psemek/geom/contains.hpp>
 
 #include <psemek/cg/convex_hull_2d/graham.hpp>
+#include <psemek/cg/body/frustum.hpp>
+#include <psemek/cg/body/box.hpp>
+#include <psemek/cg/convex/separation.hpp>
 
 #include <psemek/util/to_string.hpp>
 #include <psemek/util/hash.hpp>
@@ -966,20 +969,7 @@ void main()
 		auto const camera_position = opts.camera->position();
 		auto const camera_direction = opts.camera->direction();
 
-		geom::point<float, 3> camera_frustum_vertices[8];
-
-		for (int i = 0; i < 8; ++i)
-		{
-			geom::vector<float, 4> p;
-			p[0] = (i & 1) ? 1.f : -1.f;
-			p[1] = (i & 2) ? 1.f : -1.f;
-			p[2] = (i & 4) ? 1.f : -1.f;
-			p[3] = 1.f;
-
-			geom::gauss(camera_transform, p);
-
-			camera_frustum_vertices[i] = geom::as_point(p);
-		}
+		cg::frustum<float, 3> camera_frustum(camera_transform);
 
 		// Sort objects by mask & compute bbox
 
@@ -994,7 +984,7 @@ void main()
 			std::unordered_map<std::tuple<std::uint32_t, material const *>, objects_bucket> buckets;
 			geom::box<float, 3> bbox;
 			bool contains_near_clip = false;
-			float camera_distance = -std::numeric_limits<float>::infinity();
+			float camera_separation;
 		};
 
 		geom::box<float, 3> all_bbox;
@@ -1052,16 +1042,11 @@ void main()
 		{
 			b.bbox = geom::expand(b.bbox, b.bbox.dimensions() / 64.f);
 
-			float dist = -std::numeric_limits<float>::infinity();
-			for (int c = 0; c < 8; ++c)
-			{
-				dist = std::max(dist, dot(b.bbox.corner(c & 1, (c & 2) >> 1, (c & 4) >> 1) - camera_position, camera_direction));
-			}
-			b.camera_distance = dist;
+			b.camera_separation = cg::separation(camera_frustum, cg::box{b.bbox}).second;
 
 			b.contains_near_clip = true;
 			for (int i = 0; i < 4; ++i)
-				b.contains_near_clip &= geom::contains(b.bbox, camera_frustum_vertices[i]);
+				b.contains_near_clip &= geom::contains(b.bbox, camera_frustum.vertices[i]);
 
 			for (auto & p : b.buckets)
 			{
@@ -1078,7 +1063,7 @@ void main()
 			{
 				auto const & b = bins.data()[bi];
 
-				if (clip_by_camera && b.camera_distance < 0.f) continue;
+				if (clip_by_camera && b.camera_separation > 0.f) continue;
 
 				bool const bin_use_occlusion = clip_by_camera && !b.contains_near_clip && !b.buckets.empty() && use_occlusion;
 
@@ -1248,7 +1233,7 @@ void main()
 
 				if (b.buckets.empty()) continue;
 				if (b.contains_near_clip) continue;
-				if (b.camera_distance < 0.f) continue;
+				if (b.camera_separation > 0.f) continue;
 
 				impl().occlusion_pass_program["u_box_min"] = geom::vector{b.bbox[0].min, b.bbox[1].min, b.bbox[2].min};
 				impl().occlusion_pass_program["u_box_max"] = geom::vector{b.bbox[0].max, b.bbox[1].max, b.bbox[2].max};