Add ability to draw overlapping polygons with same transparency

[aole]

Enhancement request:

What should be added/changed?

Multiple calls to draw polygons causes the transparency to add up (transparent color provided in the color parameter to draw_polygon_filled(..).
Need a way to draw multiple polygons in one batch with the same transparency.

What would it help with?

Creating a simple top down game which has vision cones (polygon) for each of the characters. When drawing overlapping vision cones, their transparency gets added and starts looking weird.

[pvcraven]

This enhancement is not currently in process. Please re-open if you'd like to work on it. A full list of desired enhancements is available at:

http://arcade.academy/enhancement_list.html

[einarf]

This is possible by just changing the ctx.blend_func, so I'd consider this already supported. We do need an alpha blending section with more information, but that should be added later with the OpenGL stuff.