When an object is black due to divide by zero in the shader (which apparently does not throw any error, interesting), physical blur from transmission through semi-rough physical material is incorrect:
However when an object is explicitly black, it works fine:
Should (can) this be fixed within Three.js?
I think the best way to handle it is probably to validate the parameters given before compiling/updating the shader, assuming this was a built in material you were using. Since you can’t really throw an error from within a shader.
What were the parameters you passed to this material that triggered a divide by zero?
Yeah, validating on the JS side seems like the way to go, or some default values in place of 0s.
The black box behind the transparent one has a custom ShaderMaterial (arguably not enough checking on the JS side for proper values), and in the shader does this:
...
vec2 uv = fragCoord / iResolution.xy;
gl_FragColor = vec4(0.5 + 0.5 * cos(iTime + uv.xyx + vec3(0,2,4)), 1.0);
where iResolution.xy is 0,0 when the box is black.