Lighting

Astro provides some simple hardware-accelerated light and shadow support to render lighting effects in 2D. One general warning to keep in mind for these features is that these are global and not tied to any specific level. This means that is generally good practice to add all the shadows/lights at the start of a level and reset it at the end to refrain from dangling pointers (which can easily happen with these methods). See the demo in Github for a complete example of how to properly use this feature.

• add_shadow()
• add_light()
• reset()
• flush_vbo()

For a general overview of decent practices,

At the start of a level

Create all of your lights and shadows with add_light() and add_shadow(). You can add lights later at relatively low cost in terms of performance but make sure you add all your shadows at once because you need to flush_vbo() to see the changes to shadows and that method is expensive.

Throughout the level

Add/remove lights as needed, disable and move shadow objects around as desired.

At the end of the level

Call reset() and make sure none of the light/shadow variables linger to the next level to ensure minimal dangling pointers.

add_shadow()

static add_shadow(edges)

Parameters

• edges -> List A list of edges for the shadow object, in the form [[x1, y1, x2, y2], [x1, y1, x2, y2], ...]

Adds a shadow object to the lighting system and returns it. See Shadow for more information.

add_light()

static add_light(x, y, rotation, origin_x, origin_y, texture)

reset()

static reset()

Deletes all shadow objects, lights and VBOs that are currently loaded in the lighting system. You will likely want to do this between level/loading unloading scenes.

This will invalidate all variables previously acquired from add_shadow() and add_light() causing dangling pointers for any of those variables you still have in scope. For this reason you should generally want to keep the values returned by add_light() and add_shadow() local to the level scope and just reset at the end of each level.

flush_vbo()

static flush_vbo()

Once you are done adding your shadow objects you must call this method to push the shadow objects to the GPU before you may draw them.