Distance to lines results in inlets at line crossings

Hi,

I have a problem with the result that I get when calculating distances to lines in a shader program, specifically distances to multiple lines.

[ATTACH=CONFIG]645[/ATTACH]

As you can see from the screenshots there is no problem with single lines, but when combined in the calculation inlets are visible at the line crossing that I do not understand and would like to get rid of. If this is some sort of optical illusion, then I still would like to know how to avoid this.
(background: I want to create a soft shadow effect from a polygon silhouette that gets passed to the fragment shader)

Part of the fragment shader code that is used to calculate the combined distance:

void main(void) {
    outputColor = vec4(1f, 1f, 0f, 1f);
    bool bands = false;
    
    float len = 0.2;        
    float distHorizontalLine = getDistanceToLine(vec3(0f, 0f, 0f), vec3(len, 0f, 0f), currentPoint);    
    float distVerticalLine =   getDistanceToLine(vec3(0f, 0f, 0f), vec3(0f, len, 0f), currentPoint);   
    
    float dist = distHorizontalLine;                   // [A] distance to horizontal line
    dist = distVerticalLine;                           // [b] distance to vertical line
    // dist = min(distVerticalLine, distHorizontalLine);  // [C] distance to cross
    
    float radius = 0.25f;
    if (dist<radius) {
        float ratio = dist/radius;        
        vec4 distColor = vec4(0f, 0f, 1f, 1f);        
        outputColor = mix(distColor, outputColor, ratio);

        if (bands) {
            // debug: display bands
            float band = (ceil(fract(ratio)*10f))/10f;
            outputColor = vec4(band, band, 1-band, 1f);
        }        
    }    
}

The complete project (java (lwjgl) + shaders sources):

Replace min() with something else, e.g.


    dist = min(min(distVerticalLine, distHorizontalLine), distVerticalLine*distHorizontalLine/radius);

GClements thanx for the hint, I got the asked result, however I have tried to come up with a proper result (without unwanted markings), but so far I have had not much luck. I think this problem actually consist of 2 problems:
1] the calculated distances are not exactly the same for both lines, so the shader outputs a slightly different color which is visible as a discontinuous region at the ‘shadow’ intersection
[ATTACH=CONFIG]660[/ATTACH]

2] the optical illusion thing. Even when solving [1] the inlets are disturbingly visible. It just doesn’t make sense though, they should not appear in the first place.