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/**
* Draw the icons, leaving a semi-transparent rectangle on top of the icon.
*
* The top-left corner of the rectangle is rounded and drawned with anti-alias.
* The anti-alias is done by transitioning from the outer to the inner radius of
* the rounded corner, and the rectangle sides.
*/
void main()
{
/* Top-left rounded corner parameters. */
const float circle_radius_outer = 0.1;
const float circle_radius_inner = 0.075;
/**
* Add a bit transparency to see a bit of the icon, without
* getting on the way of readability. */
const float mask_transparency = 0.25;
vec2 circle_center = vec2(circle_radius_outer - text_width, 0.5);
fragColor = texture(image, texCoord_interp) * color;
/* radius in icon space (1 is the icon width). */
float radius = length(mask_coord_interp - circle_center);
float mask = smoothstep(circle_radius_inner, circle_radius_outer, radius);
bool lower_half = mask_coord_interp.y < circle_center.y;
bool right_half = mask_coord_interp.x > circle_center.x;
if (right_half && mask_coord_interp.y < circle_center.y + circle_radius_outer) {
mask = smoothstep(circle_center.y + circle_radius_inner,
circle_center.y + circle_radius_outer,
mask_coord_interp.y);
}
if (lower_half && mask_coord_interp.x > circle_center.x - circle_radius_outer) {
mask = smoothstep(circle_center.x - circle_radius_inner,
circle_center.x - circle_radius_outer,
mask_coord_interp.x);
}
fragColor = mix(vec4(0.0), fragColor, max(mask_transparency, mask));
}
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