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

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

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 ;

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

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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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

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

But i dunno any glsl methods

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

@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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Does this tutorial help. It has the basic mechanics.

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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

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what you are looking for is most likely something like this

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

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.