Dissolve/Gradient Effect

[DJO_Maverick]

Trying to throw together a custom layout at the moment (sort of porting something I did for ES a while back for personal use), and can't quite find how to achieve a certain effect.

I'd like my video snap to be in a bit of a spotlight effect, where it is rounded off (circular or ovoid...  or trapezoidal, long story) but the image dissolves at those edges.  I gather something like that would have to be done with a shader, wondering if anyone has one in use for similar purpose, or could give me some guidance on how to implement it?

Thanks,

[DJO_Maverick]

Found a solid example option in Shadertoys, but struggling to convert it to work in AM.  https://www.shadertoy.com/view/DscSW7

Original

Code: [Select]

void mainImage(out vec4 fragColor, in vec2 fragCoord)
{
    vec2 uv = fragCoord.xy / iResolution.y;
   
    float margin = 0.125;
    float radius = 0.15;
   
    vec2 halfDimensions = iResolution.xy / iResolution.y * 0.5;
   
    vec2 point = abs(uv - halfDimensions);
    vec2 corner = halfDimensions - margin - radius;
    vec2 anchor = min(point, corner);
   
    float distance = length(point - anchor);
   
    fragColor = vec4(smoothstep(radius, radius + margin, distance));
}
Modified

Code: [Select]

uniform vec2 rez;

void main()
{
float margin = 0.125;
float radius = 0.25;

    vec2 uv = gl_FragCoord.xy / rez.y;
   
    vec2 halfDimensions = rez.xy / rez.y * 0.5;
   
    vec2 point = abs(uv - halfDimensions);
    vec2 corner = halfDimensions - margin - radius;
    vec2 anchor = min(point, corner);
   
    float distance = length(point - anchor);
   
    gl_FragColor = vec4(smoothstep(radius, radius + margin, distance));
}
I know pretty much nothing about coding these myself, so I'm sure I'm missing something stupid.  At the moment, it's just changing the snap to a solid white rectangle.