[bug] drawing completely outside screen overwrites border pixels

[jzeiber]

If drawing outside the screen 1 pixel to the right or 1 pixel below the SCREEN_SIZE, the border pixels within the screen boundary are overwritten. Doing so in the top or left of the screen does not exhibit the issue.

Example:

#include "wasm4.h"

void start()
{
	PALETTE[0]=0x000000;
	PALETTE[1]=0xFF0000;
	PALETTE[2]=0x00FF00;
	PALETTE[3]=0x0000FF;
}

void update()
{
	*DRAW_COLORS=0x03;
	rect(SCREEN_SIZE-16,SCREEN_SIZE-16,16,16);
	*DRAW_COLORS=0x22;
	rect(SCREEN_SIZE,SCREEN_SIZE-16,16,16);
	rect(SCREEN_SIZE-16,SCREEN_SIZE,16,16);
	
	*DRAW_COLORS=0x03;
	rect(0,0,16,16);
	*DRAW_COLORS=0x22;
	rect(-16,0,16,16);
	rect(0,-16,16,16);
}

Result:

Expected:

[eXponenta]

Can you provide a cart file?
not reproduced on my project.

Maybe a device specific bug - how GPU query colors on missposited pixels.

[jzeiber]

Here's a cart that exhibits the issue. Tested on different computers with different browsers (Chrome/Firefox) and they all show the issue.
borderbug.zip

[aduros]

Thanks for reporting this!