From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 11 Sep 2013 08:02:43 +0000 (+0300)
Subject: Add a frustum culler class
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=2fb0370f94d74981f1a486edee37348adbf5e84e;p=libs%2Fgl.git

Add a frustum culler class
---

diff --git a/source/frustumculler.cpp b/source/frustumculler.cpp
new file mode 100644
index 00000000..5401d845
--- /dev/null
+++ b/source/frustumculler.cpp
@@ -0,0 +1,53 @@
+#include "camera.h"
+#include "frustumculler.h"
+#include "renderable.h"
+#include "renderer.h"
+
+#include <msp/io/print.h>
+
+namespace Msp {
+namespace GL {
+
+void FrustumCuller::setup_frame(const Renderer &renderer)
+{
+	const Camera *camera = renderer.get_camera();
+	if(!camera)
+		return;
+
+	float y = tan(camera->get_field_of_view()/2.0f);
+	float s = sqrt(y*y+1);
+	edges[0] = Vector3(0, 1/s, y/s);
+	edges[1] = Vector3(0, -1/s, y/s);
+
+	float x = y*camera->get_aspect();
+	s = sqrt(x*x+1);
+	edges[2] = Vector3(1/s, 0, x/s);
+	edges[3] = Vector3(-1/s, 0, x/s);
+}
+
+bool FrustumCuller::cull(const Renderer &renderer, const Renderable &renderable) const
+{
+	const Matrix *matrix = renderable.get_matrix();
+	const Geometry::BoundingSphere<float, 3> *bsphere = renderable.get_bounding_sphere();
+	const Camera *camera = renderer.get_camera();
+	if(!matrix || !bsphere || !camera)
+		return false;
+
+	Matrix mvm = camera->get_matrix()**matrix;
+	float n = camera->get_near_clip();
+	float f = camera->get_far_clip();
+
+	Vector3 center = mvm*bsphere->get_center();
+	float radius = bsphere->get_radius();
+
+	if(center.z-radius>-n || center.z+radius<-f)
+		return true;
+	for(unsigned i=0; i<4; ++i)
+		if(dot(center, edges[i])>radius)
+			return true;
+
+	return false;
+}
+
+} // namespace GL
+} // namespace Msp
diff --git a/source/frustumculler.h b/source/frustumculler.h
new file mode 100644
index 00000000..d6f07486
--- /dev/null
+++ b/source/frustumculler.h
@@ -0,0 +1,24 @@
+#ifndef MSP_GL_FRUSTUMCULLER_H_
+#define MSP_GL_FRUSTUMCULLER_H_
+
+#include "culler.h"
+#include "vector.h"
+
+namespace Msp {
+namespace GL {
+
+class FrustumCuller: public Culler
+{
+private:
+	Vector3 edges[4];
+
+public:
+	virtual void setup_frame(const Renderer &);
+
+	virtual bool cull(const Renderer &, const Renderable &) const;
+};
+
+} // namespace GL
+} // namespace Msp
+
+#endif