def maybe_update_matrices(self, gl):
update_transform = self.must_update_view or self.must_update_projection
if self.must_update_view:
self.update_view(gl)
self.must_update_view = False
if self.must_update_projection:
self.update_perspective(gl)
self.must_update_projection = False
if update_transform:
# Device coordinates are a square from (-1, -1) to (1, 1). Screen
# coordinates are (0, 0) to (width, height). Both coordinates
# are useful in different circumstances, so we'll pre-compute
# matrices to do the transformations from world coordinates
# into each of these.
transform_to_device = Matrix4x4.multiply_MM(self.projection_matrix, self.view_matrix)
translate = Matrix4x4.create_translation(1.0, 1.0, 0.0)
scale = Matrix4x4.create_scaling(self.render_state.screen_width * 0.5,
self.render_state.screen_height * 0.5, 1)
transform_to_screen = \
Matrix4x4.multiply_MM(Matrix4x4.multiply_MM(scale, translate), transform_to_device)
self.render_state.set_tranformation_matrices(transform_to_device, transform_to_screen)
