# Simple flat mesh, sits on the axes X and Z, normal on Y
class Plane
	super Mesh

	# TODO allow for complex rotation, either at creation or in Actor

	# Modifier to `texture_coords` to repeat the texture on the X axis
	#
	# At 1.0, the texture is stretched to cover the whole plane.
	# If greater than 1.0, the texture is repeated.
	#
	# This value must be set before using `texture_coords` or drawing this plane.
	var repeat_x = 1.0 is writable

	# Modifier to `texture_coords` to repeat the texture on the Y axis
	#
	# At 1.0, the texture is stretched to cover the whole plane.
	# If greater than 1.0, the texture is repeated.
	#
	# This value must be set before using `texture_coords` or drawing this plane.
	var repeat_y = 1.0 is writable

	redef var vertices is lazy do
		var a = [-0.5, 0.0, -0.5]
		var b = [ 0.5, 0.0, -0.5]
		var c = [-0.5, 0.0,  0.5]
		var d = [ 0.5, 0.0,  0.5]

		var vertices = new Array[Float]
		for v in [c, d, a, b] do vertices.add_all v
		return vertices
	end

	redef var normals: Array[Float] is lazy do
		var normals = new Array[Float]
		for i in 4.times do normals.add_all([0.0, 1.0, 0.0])
		return normals
	end

	redef var texture_coords: Array[Float] is lazy do
		var offset_left = 0.0
		var offset_top = 0.0
		var offset_right = 1.0*repeat_x
		var offset_bottom = 1.0*repeat_y
		var a = [offset_left,  offset_bottom]
		var b = [offset_right, offset_bottom]
		var c = [offset_left,  offset_top]
		var d = [offset_right, offset_top]

		var texture_coords = new Array[Float]
		for v in [c, d, a, b] do texture_coords.add_all v
		return texture_coords
	end

	redef var center = new Point3d[Float](0.0, 0.0, 0.0) is lazy

	init do indices.add_all([0, 1, 2, 2, 1, 3])
	# TODO use gl_TRIANGLE_FAN instead
end