Rectangle not overlaying on line correctly

[arihantparsoya]

Drawing a rectangle over a line does not fully obscure the line

To Reproduce

from p5 import *

def setup():
	size(640, 360)
	no_loop()

def draw():
	background(0)
	stroke(255)
	line((0, 0), (200, 200))
	fill(255, 0, 0)
	rect((60, 50), 50, 50)

if __name__ == '__main__':
	run()

Output

I believe the problem is in the renderer. The renderer first renders all the polygons before lines. Reference: https://github.com/p5py/p5/blob/master/p5/sketch/renderer.py#L276

System information:

• p5 release (version number or latest commit):
• Python version: 3.7
• Operating system: MacOS Mojave

[abhikpal]

This looks like #67.

[jeremydouglass]

A guess (not an OpenGL expert) is that you need to get rid of globals poly_draw_queue, line_draw_queue, point_draw_queue and replace them with a single draw_queue.

So, in add_to_draw, append like this this:

    draw_queue.append(('poly', vertices, idx, fill))
    draw_queue.append(('point', vertices, idx, stroke))
    draw_queue.append(('line', vertices, idx, stroke))

...and then flush_geometry needs to iterate over that existing labeled queue -- rather than building it manually with zip() out of three small queues.

p5/p5/sketch/renderer.py

Lines 393 to 395 in 000b562

	global poly_draw_queue
	global line_draw_queue
	global point_draw_queue

[arihantparsoya]

When we use a common draw_queue, OpenGL is called multiple times whenever the opengl primitives (triangles, lines, triangles) change. This makes the overall efficiency of code slower. Hence, this structure was adopted.

In the current development branch, we have implemented a common draw_queue with some performance optimisation. It will be merged into the main code soon.