Mix textures of different sizes in the fragment shader

[Borodin]

I have two texture maps of different sizes.
colorMap - 1024x1024 px
alphaMap - 32x32 px

I want to use the color from the colorMap and the transparency from the alphaMap.

However, I get the result, as if the maps passed to the shader are the same. If I use the cards individually, then everything works in the expected way.

varying vec3 vWorldPosition;
varying vec2 vUv;

uniform sampler2D colorMap;
uniform sampler2D alphaMap;

void main(){
    gl_FragColor.rgb = texture2D(colorMap, vUv).rgb;
    gl_FragColor.a = texture2D(alphaMap, vUv).a;
}

I also tried mixing two cards. As a result, I get a duplication of a lower resolution map

void main(){
    gl_FragColor = mix(texture2D(colorMap, vUv), texture2D(alphaMap, vUv), 0.5);
}

I would appreciate any help on my issue.

[prisoner849]

@Borodin

I have two texture maps of different sizes.

and then suddenly

@Borodin

If I use the cards individually,

Could you provide more details about what you do, what you have and what you want to achieve?
Would be great to provide a minimal editable working example.

[Borodin]

I slightly modified the example for better clarity. I found that the problem is observed only in release > 135
cranky-elgamal-8nie14 - CodeSandbox — working example
I expect to see a sphere like this in release > 135

What do I need to change in the code to work in the current release?

[prisoner849]

Haven’t dig too deep, but in the latter releases, when you instantiate a DataTexture, you have to set dataTexture.needsUpdate = true; right after it.

[prisoner849]

I went another way to achieve the visual you provided: https://codepen.io/prisoner849/full/PoazXJR