From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 2 Aug 2016 22:26:37 +0000 (+0300)
Subject: Support rotating the camera frustum
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=aa4d7203c90083af7fbcbe8368e55ad2f29d5ff1;p=libs%2Fgl.git

Support rotating the camera frustum

The rotation is applied as the very last step of projection, alllowing
screen rotation to be easily implemented in software.
---

diff --git a/source/camera.cpp b/source/camera.cpp
index d119e1ef..ba8ff718 100644
--- a/source/camera.cpp
+++ b/source/camera.cpp
@@ -56,6 +56,12 @@ void Camera::set_frustum_axis(float x, float y)
 	update_projection_matrix();
 }
 
+void Camera::set_frustum_rotation(const Geometry::Angle<float> &r)
+{
+	rotate = r;
+	update_projection_matrix();
+}
+
 void Camera::set_position(const Vector3 &p)
 {
 	position = p;
@@ -115,6 +121,7 @@ void Camera::update_projection_matrix()
 		proj_matrix = Matrix::frustum(left, right, bottom, top, clip_near, clip_far);
 	else
 		proj_matrix = Matrix::ortho(left, right, bottom, top, clip_near, clip_far);
+	proj_matrix = Matrix::rotation(rotate, Vector3(0, 0, 1))*proj_matrix;
 }
 
 void Camera::update_object_matrix()
diff --git a/source/camera.h b/source/camera.h
index 9a525e6b..f814e9d7 100644
--- a/source/camera.h
+++ b/source/camera.h
@@ -18,6 +18,7 @@ private:
 	float clip_far;
 	float frustum_x;
 	float frustum_y;
+	Geometry::Angle<float> rotate;
 	Vector3 position;
 	Vector3 look_dir;
 	Vector3 up_dir;
@@ -33,10 +34,12 @@ public:
 	void set_aspect(float);
 	void set_depth_clip(float, float);
 	void set_frustum_axis(float, float);
+	void set_frustum_rotation(const Geometry::Angle<float> &);
 	const Geometry::Angle<float> &get_field_of_view() const { return fov; }
 	float get_aspect() const { return aspect; }
 	float get_near_clip() const { return clip_near; }
 	float get_far_clip() const { return clip_far; }
+	const Geometry::Angle<float> &get_frustum_rotation() const { return rotate; }
 
 	void set_position(const Vector3 &);
 	void set_look_direction(const Vector3 &);