From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 13 Mar 2022 09:42:53 +0000 (+0200)
Subject: Move frustum culling from Scene to Camera
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=4f2f558123db15393607d8b21b949d7798561dec;p=libs%2Fgl.git

Move frustum culling from Scene to Camera

Also refactor it so that the camera's object matrix is accounted for
when computing the frustum planes.
---

diff --git a/source/render/camera.cpp b/source/render/camera.cpp
index 3ace92b9..7ffe0c15 100644
--- a/source/render/camera.cpp
+++ b/source/render/camera.cpp
@@ -125,6 +125,27 @@ Vector3 Camera::unproject(const Vector3 &p) const
 	return unproject(Vector4(p.x, p.y, p.z, 1.0f)).slice<3>(0);
 }
 
+bool Camera::is_in_frustum(const Renderable &renderable) const
+{
+	const Matrix *rmatrix = renderable.get_matrix();
+	const Geometry::BoundingSphere<float, 3> *bsphere = renderable.get_bounding_sphere();
+	if(!rmatrix || !bsphere)
+		return true;
+
+	Vector4 center = *rmatrix*compose(bsphere->get_center(), 1.0f);
+	Vector3 x_axis = (rmatrix->column(0)*bsphere->get_radius()).slice<3>(0);
+	float radius_sq = inner_product(x_axis, x_axis);
+
+	for(unsigned i=0; i<6; ++i)
+	{
+		float distance = inner_product(center, frustum_planes[i]);
+		if(distance<0 && distance*distance>radius_sq)
+			return false;
+	}
+
+	return true;
+}
+
 void Camera::update_projection_matrix()
 {
 	float frustum_h = (fov!=Geometry::Angle<float>::zero() ? tan(fov/2.0f)*clip_near : height/2);
@@ -141,6 +162,8 @@ void Camera::update_projection_matrix()
 
 	shdata.uniform("clip_eye_matrix", proj_matrix);
 	shdata.uniform("eye_clip_matrix", invert(proj_matrix));
+
+	update_frustum_planes();
 }
 
 void Camera::update_object_matrix()
@@ -156,6 +179,43 @@ void Camera::update_object_matrix()
 
 	shdata.uniform("world_eye_matrix", matrix);
 	shdata.uniform("eye_world_matrix", view_matrix);
+
+	update_frustum_planes();
+}
+
+void Camera::update_frustum_planes()
+{
+	// TODO Handle off-center and rotated frustums
+	if(is_orthographic())
+	{
+		frustum_planes[0] = Vector4(0, 1, 0, height);
+		frustum_planes[1] = Vector4(0, -1, 0, height);
+
+		frustum_planes[2] = Vector4(1, 0, 0, height*aspect);
+		frustum_planes[3] = Vector4(-1, 0, 0, height*aspect);
+	}
+	else
+	{
+		float y = tan(fov/2.0f);
+		float s = sqrt(y*y+1);
+		frustum_planes[0] = Vector4(0, 1/s, -y/s, 0);
+		frustum_planes[1] = Vector4(0, -1/s, -y/s, 0);
+
+		float x = y*aspect;
+		s = sqrt(x*x+1);
+		frustum_planes[2] = Vector4(1/s, 0, -x/s, 0);
+		frustum_planes[3] = Vector4(-1/s, 0, -x/s, 0);
+	}
+
+	frustum_planes[4] = Vector4(0, 0, 1, clip_far);
+	frustum_planes[5] = Vector4(0, 0, -1, -clip_near);
+
+	for(unsigned i=0; i<6; ++i)
+	{
+		Vector3 normal = frustum_planes[i].slice<3>(0);
+		normal = (matrix*compose(normal, 0.0f)).slice<3>(0);
+		frustum_planes[i] = compose(normal, frustum_planes[i].w-dot(normal, matrix.column(3).slice<3>(0)));
+	}
 }
 
 void Camera::set_debug_name(const string &name)
diff --git a/source/render/camera.h b/source/render/camera.h
index cb9b4ce1..59a0ac2e 100644
--- a/source/render/camera.h
+++ b/source/render/camera.h
@@ -57,6 +57,7 @@ private:
 	Matrix view_matrix;
 	Matrix proj_matrix;
 	ProgramData shdata;
+	Vector4 frustum_planes[6];
 
 public:
 	Camera();
@@ -124,9 +125,12 @@ public:
 	/** Returns a ProgramData object containing the camera matrices. */
 	const ProgramData &get_shader_data() const { return shdata; }
 
+	bool is_in_frustum(const Renderable &) const;
+
 private:
 	void update_projection_matrix();
 	void update_object_matrix();
+	void update_frustum_planes();
 
 public:
 	void set_debug_name(const std::string &);
diff --git a/source/render/occludedscene.cpp b/source/render/occludedscene.cpp
index 644e380d..cb37a60e 100644
--- a/source/render/occludedscene.cpp
+++ b/source/render/occludedscene.cpp
@@ -95,10 +95,9 @@ void OccludedScene::render(Renderer &renderer, Tag tag) const
 	float frustum_h = tan(camera->get_field_of_view()/2.0f)*2.0f;
 
 	// Perform frustum culling and render any major occluders
-	bool use_frustum = setup_frustum(renderer);
 	for(auto i=occluded_cache.begin(); (i!=occluded_cache.end() && i->renderable); ++i)
 	{
-		i->in_frustum = (!use_frustum || !frustum_cull(*i->renderable));
+		i->in_frustum = camera->is_in_frustum(*i->renderable);
 		if(!i->in_frustum)
 			continue;
 
diff --git a/source/render/orderedscene.cpp b/source/render/orderedscene.cpp
index 48ad7d64..a62087e3 100644
--- a/source/render/orderedscene.cpp
+++ b/source/render/orderedscene.cpp
@@ -1,4 +1,5 @@
 #include <msp/core/algorithm.h>
+#include "camera.h"
 #include "orderedscene.h"
 #include "renderer.h"
 
@@ -48,10 +49,10 @@ void OrderedScene::finish_frame()
 
 void OrderedScene::render(Renderer &renderer, Tag tag) const
 {
-	if(setup_frustum(renderer))
+	if(const Camera *camera = renderer.get_camera())
 	{
 		for(Renderable *r: content)
-			if(!frustum_cull(*r))
+			if(camera->is_in_frustum(*r))
 				r->render(renderer, tag);
 	}
 	else
diff --git a/source/render/scene.cpp b/source/render/scene.cpp
index 0f773722..a9cf8f96 100644
--- a/source/render/scene.cpp
+++ b/source/render/scene.cpp
@@ -15,64 +15,6 @@ using namespace std;
 namespace Msp {
 namespace GL {
 
-bool Scene::setup_frustum(const Renderer &renderer) const
-{
-	const Camera *camera = renderer.get_camera();
-	if(!camera)
-		return false;
-
-	culling_matrix = camera->get_view_matrix()*renderer.get_matrix();
-
-	if(camera->is_orthographic())
-	{
-		float h = camera->get_orthographic_height();
-		frustum_edges[0] = Vector4(0, 1, 0, -h);
-		frustum_edges[1] = Vector4(0, -1, 0, -h);
-
-		float w = camera->get_orthographic_width();
-		frustum_edges[2] = Vector4(1, 0, 0, -w);
-		frustum_edges[3] = Vector4(-1, 0, 0, -w);
-	}
-	else
-	{
-		float y = tan(camera->get_field_of_view()/2.0f);
-		float s = sqrt(y*y+1);
-		frustum_edges[0] = Vector4(0, 1/s, y/s, 0);
-		frustum_edges[1] = Vector4(0, -1/s, y/s, 0);
-
-		float x = y*camera->get_aspect_ratio();
-		s = sqrt(x*x+1);
-		frustum_edges[2] = Vector4(1/s, 0, x/s, 0);
-		frustum_edges[3] = Vector4(-1/s, 0, x/s, 0);
-	}
-
-	frustum_edges[4] = Vector4(0, 0, -1, -camera->get_far_clip());
-	frustum_edges[5] = Vector4(0, 0, 1, camera->get_near_clip());
-
-	return true;
-}
-
-bool Scene::frustum_cull(const Renderable &renderable) const
-{
-	const Matrix *matrix = renderable.get_matrix();
-	const Geometry::BoundingSphere<float, 3> *bsphere = renderable.get_bounding_sphere();
-	if(!matrix || !bsphere)
-		return false;
-
-	Vector4 center = culling_matrix*(*matrix*compose(bsphere->get_center(), 1.0f));
-	Vector3 x_axis = (matrix->column(0)*bsphere->get_radius()).slice<3>(0);
-	float radius_sq = inner_product(x_axis, x_axis);
-
-	for(unsigned i=0; i<6; ++i)
-	{
-		float distance = inner_product(center, frustum_edges[i]);
-		if(distance>0 && distance*distance>radius_sq)
-			return true;
-	}
-
-	return false;
-}
-
 Scene::GenericLoader::TypeRegistry &Scene::get_scene_registry()
 {
 	static Scene::GenericLoader::TypeRegistry registry;
diff --git a/source/render/scene.h b/source/render/scene.h
index d07a81da..6f4f48d6 100644
--- a/source/render/scene.h
+++ b/source/render/scene.h
@@ -60,7 +60,6 @@ public:
 
 protected:
 	mutable Matrix culling_matrix;
-	mutable Vector4 frustum_edges[6];
 
 	Scene() = default;
 public:
@@ -69,11 +68,6 @@ public:
 	virtual void add(Renderable &) = 0;
 	virtual void remove(Renderable &) = 0;
 
-protected:
-	bool setup_frustum(const Renderer &) const;
-	bool frustum_cull(const Renderable &) const;
-
-public:
 	template<typename T>
 	static void register_type(const std::string &);
 private:
diff --git a/source/render/simplescene.cpp b/source/render/simplescene.cpp
index 68db812b..e78b4709 100644
--- a/source/render/simplescene.cpp
+++ b/source/render/simplescene.cpp
@@ -1,4 +1,5 @@
 #include <msp/core/algorithm.h>
+#include "camera.h"
 #include "renderer.h"
 #include "simplescene.h"
 
@@ -33,10 +34,10 @@ void SimpleScene::finish_frame()
 
 void SimpleScene::render(Renderer &renderer, Tag tag) const
 {
-	if(setup_frustum(renderer))
+	if(const Camera *camera = renderer.get_camera())
 	{
 		for(Renderable *r: content)
-			if(!frustum_cull(*r))
+			if(camera->is_in_frustum(*r))
 				r->render(renderer, tag);
 	}
 	else
diff --git a/source/render/zsortedscene.cpp b/source/render/zsortedscene.cpp
index 25255dc6..9c56f26e 100644
--- a/source/render/zsortedscene.cpp
+++ b/source/render/zsortedscene.cpp
@@ -81,10 +81,9 @@ void ZSortedScene::render(Renderer &renderer, Tag tag) const
 	float radius_factor = reference-1.0f;
 	float sign = 1.0f-order*2.0f;
 
-	bool use_frustum = setup_frustum(renderer);
 	for(SortedRenderable &r: sorted_cache)
 	{
-		r.in_frustum = (!use_frustum || !frustum_cull(*r.renderable));
+		r.in_frustum = camera->is_in_frustum(*r.renderable);
 		if(!r.in_frustum)
 			continue;