redef class Material
	# Optimized draw of `model`, a part of `actor`, from the view of `camera`
	#
	# This drawing should only produce usable depth data. The default behavior,
	# uses `shadow_depth_program`.
	protected fun draw_depth(actor: Actor, model: LeafModel, camera: Camera)
	do
		var program = app.shadow_depth_program
		program.use
		program.mvp.uniform camera.mvp_matrix

		var mesh = model.mesh

		program.translation.uniform(actor.center.x, actor.center.y, actor.center.z, 0.0)
		program.scale.uniform actor.scale
		program.use_map_diffuse.uniform false

		program.tex_coord.array_enabled = true
		program.tex_coord.array(mesh.texture_coords, 2)

		program.coord.array_enabled = true
		program.coord.array(mesh.vertices, 3)

		program.rotation.uniform new Matrix.gamnit_euler_rotation(actor.pitch, actor.yaw, actor.roll)

		if mesh.indices.is_empty then
			glDrawArrays(mesh.draw_mode, 0, mesh.vertices.length/3)
		else
			glDrawElements(mesh.draw_mode, mesh.indices.length, gl_UNSIGNED_SHORT, mesh.indices_c.native_array)
		end
	end

end

redef class Material
	# Get the default blueish material
	new do return new SmoothMaterial(
		[0.0, 0.0, 0.3, 1.0],
		[0.0, 0.0, 0.6, 1.0],
		[1.0, 1.0, 1.0, 1.0])
end

redef class Material

	# Draw `actor` to selection values
	protected fun draw_selection(actor: Actor, model: LeafModel, id: Int)
	do
		var program = app.selection_program
		var mesh = model.mesh

		draw_selection_texture(actor, model)

		program.translation.uniform(actor.center.x, actor.center.y, actor.center.z, 0.0)
		program.scale.uniform actor.scale

		program.coord.array_enabled = true
		program.coord.array(mesh.vertices, 3)
		program.rotation.uniform new Matrix.gamnit_euler_rotation(actor.pitch, actor.yaw, actor.roll)

		var display = app.display
		assert display != null
		var r = display.red_bits
		var g = display.green_bits
		var b = display.blue_bits

		# Build ID as a color
		var p1 = id & ((2**r)-1)
		var p2 = id >> r & ((2**g)-1)
		var p3 = id >> (r+g) & ((2**b)-1)
		program.color_id.uniform(
			p1.to_f/((2**r)-1).to_f,
			p2.to_f/((2**g)-1).to_f,
			p3.to_f/((2**b)-1).to_f, 1.0)

		if mesh.indices.is_empty then
			glDrawArrays(mesh.draw_mode, 0, mesh.vertices.length/3)
		else
			glDrawElements(mesh.draw_mode, mesh.indices.length, gl_UNSIGNED_SHORT, mesh.indices_c.native_array)
		end
	end

	private fun draw_selection_texture(actor: Actor, model: LeafModel)
	do
		var program = app.selection_program
		program.use_map_diffuse.uniform false
	end
end