Drawing particles to surface issues

[abeldev]

I have a basic lighting system and basic fog particle system that is placed over the lighting system. The fog can get pretty thick and hence disrupts visibility so I wanted to draw the fog particles to a surface so I could cut out holes in the fog similar to the lighting system. However when I attempt to draw the fog to a surface using part_system_drawit() and setting part_system_automatic_draw() to 0, the fog turns black and the alpha is incredibly low to the point where you can't even see it.


Particle system without being drawn to surface and part_system_automatic_draw set to 1:

https://imgur.com/Pjy25J1


Particle system when I attempt to draw it to a surface and automatic_draw set to 0:
(The fog is actually present just really low opacity and has turned black for some reason)

https://imgur.com/3U4R0If


Draw event of fog particles:

if (!surface_exists(global.fog_surface)) {
global.fog_surface = surface_create(room_width, room_height);
}

surface_set_target(global.fog_surface);

part_system_drawit(global.part_fog_system);
//Fog light is just an object that surrounds the player and is meant to subtract from particle surface so players can see through fog
gpu_set_blendmode(bm_subtract);
with(obj_fogLight) {
draw_self();
}
gpu_set_blendmode(bm_normal);


// reset target and draw the surface
surface_reset_target();

draw_surface_ext(global.fog_surface,0,0,1,1,0,0,1);

Any idea why drawing the particle system to a surface is changing it so much? How do I go about replicated how the particles look normally, on a surface?

 

[Nocturne]

This issue is due to the way that surfaces deal with alpha... There is a tech blog about this here: https://www.yoyogames.com/blog/60/alpha-and-surfaces

At the end, there are some solutions given, but note that the functions are listed as the GM:S 1.4 versions, so be sure to change them to the "gpu_" versions if you're using GMS2.

 

[abeldev]

Hmmm none of these solutions seem to work for me. I think it might be because the particles fade from 0 to 1, and back down to 0 again?

 

[FoufaDjo]

draw_surface_ext(global.fog_surface,0,0,1,1,0,0,1); cet color to c_white