GameMaker [SOLVED] alpha blending issues

[dirkinz]

I have a game in which the player can essentially draw a line by dragging an object around. The line (made with draw_line_width()) is somewhat transparent and that's where the issue comes in. If the player draws back over the line it adds the alpha of the old line and the new line together. I want the line to display at a constant transparency no matter how many times it gets layered over itself. I'm just starting to look at blend modes and surfaces and I think they are the answer but I'm a bit overwhelmed by them. I'm unsure of the best way to accomplish this.

solved:

iirc it's just:

draw_set_alpha(/* alpha */);
    draw_surface(/* your surface stuff */);
draw_set_alpha(1);

or draw_surface_ext() if you prefer.

 

[Guest User]

none of your images are working for me but i would think the solution to this is simply drawing the lines themselves as opaque (alpha = 1) and drawing the surface itself with decreased alpha a/o blend modes.

 

[dirkinz]

none of your images are working for me but i would think the solution to this is simply drawing the lines themselves as opaque (alpha = 1) and drawing the surface itself with decreased alpha a/o blend modes.

Sorry about the images. That makes a lot of sense. I was having trouble finding how to change the alpha of a surface though. I'll give it annoys look in the morning with a fresh mind though.

 

[Guest User]

iirc it's just:

draw_set_alpha(/* alpha */);
    draw_surface(/* your surface stuff */);
draw_set_alpha(1);

or draw_surface_ext() if you prefer.

 

[dirkinz]

ok. awesome. I didn't realize that draw_set_alpha() would affect the drawing of whole surfaces. Thank you so much for the help.