From e645768be035f155e1deda931079cf1e84851a86 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 6 Nov 2016 00:20:40 +0200
Subject: [PATCH] Use an orthographic camera for rendering the shadow map

---
 source/shadowmap.cpp | 45 ++++++++++++--------------------------------
 source/shadowmap.h   |  2 --
 2 files changed, 12 insertions(+), 35 deletions(-)

diff --git a/source/shadowmap.cpp b/source/shadowmap.cpp
index bc46f2c1..4ad192ca 100644
--- a/source/shadowmap.cpp
+++ b/source/shadowmap.cpp
@@ -64,41 +64,18 @@ void ShadowMap::setup_frame() const
 	rendered = true;
 	renderable.setup_frame();
 
+	Camera camera;
 	const Vector4 &lpos = light.get_position();
-	Vector3 back;
-	if(lpos.w)
-	{
-		/* XXX Not really proper way to support positional lights, but good
-		enough when the light source is far away */
-		back = lpos.slice<3>(0)-target;
-	}
-	else
-		back = lpos.slice<3>(0);
-	back.normalize();
-
-	Vector3 up;
-	if(abs(back.z)<0.99)
-		up = Vector3(0, 0, 1);
-	else
-		up = Vector3(0, 1, 0);
-
-	Vector3 right = normalize(cross(up, back));
+	/* XXX Not really proper way to support positional lights, but good
+	enough when the light source is far away */
+	camera.set_look_direction(lpos.w*target-lpos.slice<3>(0));
 
-	Vector4 columns[4];
-	columns[0] = compose(right, 0.0f);
-	columns[1] = compose(normalize(cross(back, right)), 0.0f);
-	columns[2] = compose(back, 0.0f);
-	columns[3] = compose(target, 1.0f);
-	light_matrix = Matrix::from_columns(columns);
-	view_matrix = invert(light_matrix);
+	camera.set_up_direction((abs(camera.get_look_direction().z)<0.99) ? Vector3(0, 0, 1) : Vector3(0, 1, 0));
+	camera.set_position(target);
+	camera.set_orthographic(radius*2, radius*2);
+	camera.set_depth_clip(-radius, radius);
 
-	MatrixStack::Push push_mv(MatrixStack::modelview());
-	MatrixStack::Push push_proj(MatrixStack::projection());
-
-	MatrixStack::projection() = Matrix::ortho(-radius, radius, -radius, radius, -radius, radius);
-	MatrixStack::modelview() = view_matrix;
-
-	shadow_matrix = light_matrix;
+	shadow_matrix = camera.get_object_matrix();
 	shadow_matrix.scale(radius*2, radius*2, -radius*2);
 	shadow_matrix.translate(-0.5, -0.5, depth_bias/size-0.5);
 	shadow_matrix.invert();
@@ -106,7 +83,9 @@ void ShadowMap::setup_frame() const
 	BindRestore bind_fbo(fbo);
 	Bind bind_depth(DepthTest::lequal());
 	fbo.clear(DEPTH_BUFFER_BIT);
-	renderable.render("shadow");
+
+	Renderer renderer(&camera);
+	renderable.render(renderer, "shadow");
 }
 
 void ShadowMap::finish_frame() const
diff --git a/source/shadowmap.h b/source/shadowmap.h
index 3757b1f1..119d369c 100644
--- a/source/shadowmap.h
+++ b/source/shadowmap.h
@@ -25,8 +25,6 @@ private:
 	unsigned size;
 	const Light &light;
 	mutable Framebuffer fbo;
-	mutable Matrix light_matrix;
-	mutable Matrix view_matrix;
 	mutable Matrix shadow_matrix;
 	Texture2D depth_buf;
 	Vector3 target;
-- 
2.43.0