# Draw the light view in the bottom left of the screen, for debugging only
	#
	# The shadow depth texture is a square that can be deformed by this projection.
	protected fun frame_core_shadow_debug(display: GamnitDisplay)
	do
		if not supports_shadows then
			print_error "Error: Shadows are not supported by the current hardware configuration"
			return
		end

		perf_clock_shadow.lapse

		var program = shadow_debug_program

		glBindBuffer(gl_ARRAY_BUFFER, shadow_context.buffer_array)
		glViewport(0, 0, display.width/3, display.height/3)
		glClear gl_DEPTH_BUFFER_BIT
		program.use

		# Uniforms
		glActiveTexture gl_TEXTURE0
		glBindTexture(gl_TEXTURE_2D, shadow_context.depth_texture)
		program.texture.uniform 0

		# Attributes
		var sizeof_gl_float = 4
		var n_floats = 3
		glEnableVertexAttribArray program.coord.location
		glVertexAttribPointeri(program.coord.location, n_floats, gl_FLOAT, false, 0, 0)
		var offset = 4 * n_floats * sizeof_gl_float

		n_floats = 2
		glEnableVertexAttribArray program.tex_coord.location
		glVertexAttribPointeri(program.tex_coord.location, n_floats, gl_FLOAT, false, 0, offset)
		var gl_error = glGetError
		assert gl_error == gl_NO_ERROR else print_error gl_error

		# Draw
		glDrawArrays(gl_TRIANGLE_STRIP, 0, 4)
		gl_error = glGetError
		assert gl_error == gl_NO_ERROR else print_error gl_error

		# Take down
		glBindBuffer(gl_ARRAY_BUFFER, 0)
		gl_error = glGetError
		assert gl_error == gl_NO_ERROR else print_error gl_error

		sys.perfs["gamnit shadow debug"].add app.perf_clock_shadow.lapse
	end