Request : 2D filter to make close objects semi-transparent

Game Engine Game Engine Support and Discussion
1

As i tried/struggle to find solutions with rays , materials and changing alpha channel of objects, i was wondering if applying a 2d filter wouldnt make things easier and more elegant

I have no knowledges in glsl so i was wondering if someone can help me program a 2d filter in which , below an X distance of the focal point of the camera (X would be the distance camera - character) , the more a vertex is close to the camera, the more it will be transparent … kinda “reverse fog”

?

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2

Not sure of the glsl method, but I think I might be able to do this with python, will try to code it tommorow

3

its a 2d filter, it has to be in glsl (opengl)

I can easily set the r,g,b channels but the alpha channel doesnt operate

uniform sampler2D bgl_RenderedTexture;
 
void main(void)
{
    vec4 color = texture2D(bgl_RenderedTexture, gl_TexCoord[0].st); 
    vec4 temp = color.rgba ;
    temp.a = 0.2 ;
    gl_FragColor = temp ;
}
4

im pretty sure transparency needs to be enabled on the material, ive had this happen before.

5

i just tested, it doesnt change the thing.
Ofc, i cant modify the alpha of the object, but here’s it really the pixels of the scene that are targeted

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6

You can modify the alpha of an object with python with this

C = logic.getCurrentControllers
O = C.owner

o.color = [r, g, b, a] #r =red values, g = green, b = blue and a = alpha values
7

We could use the near sensor in some way to manipulate the alpha values with this code, thats what I was saying

8

But i dunno any glsl methods

9

Its a misunderstood of me ; 2d filters are only a process on a rendered image , so its impossible to “scratch” the pixel to see what’s hidden behind in order to blend both … so transparency - blending front pixels with “back” pixels is not an option.

@Daedalus_MDW kindly helped the newbie i am with materials and gave me a conveniant solution. Thx to him

673×610 71.3 KB

@ANSH, it was not about dynalicaly setting a color to an object, (i use this to underline a target selection for example) but more acting on a “pixel level” .

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10

Does this tutorial help. It has the basic mechanics.

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11

yeah that’s pretty cool too. Will test it tomorrow. The only thing is that it doesnt seem to use distances. Will see tomorrow with Math nodes

12

what you are looking for is most likely something like this

Screenshot_20201215_234652
Screenshot_20201215_2346521920×1048 232 KB

transparent-by-distance.blend (532.2 KB)

it is basically the same technique used in Yo Frankie! to make leaves transparent when you got close.

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13

greater/less than math node would be much more efficient when paired with clip

14

i used clip here to get a clear hole, normally you would use alpha blend to get soft edges and see thru, and the other reason i used a color ramp where laziness, it is a fast way to clip the result in the 0 to 1 space.

and another reason is who cares if it works.

15

linked