minimal optimisations lol

varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform sampler2D interior;
uniform vec3 u_color;
#define OUTLINE_RADIUS 4.0
#define ASPECT_X (1.0/800.0)
#define ASPECT_Y (1.0/608.0)

void main() {
    vec3 outline_color = u_color/255.0;
    // Final alpha of the fragment (for cutout effect)
    float final_alpha = texture2D(gm_BaseTexture, v_vTexcoord).a;

    // Interior color of the fragment (for interior effect)
    vec3 interior_color = texture2D(interior, v_vTexcoord).rgb;

    // Minimum distance to non-interior (for outline efect)
    float mindist_squared = 17.0;
    for (int oy = -OUTLINE_RADIUS; oy <= OUTLINE_RADIUS; oy += 1) {
        for (int ox = -OUTLINE_RADIUS; ox <= OUTLINE_RADIUS; ox += 1) {
            vec4 geom_test = texture2D(gm_BaseTexture, v_vTexcoord+vec2(ox * ASPECT_X, oy * ASPECT_Y));
            float distsquared = ox * ox + oy * oy;
            mindist_squared = min(  mindist_squared,
                                    mix(distsquared, 999.0, geom_test.a));
        }
    }
    float outline_strength =(sqrt(mindist_squared)/OUTLINE_RADIUS);
    float final_outline = smoothstep(0.4, 0.8, outline_strength);
    float solid_alpha = smoothstep(0.75, 0.95, final_alpha);

    gl_FragColor = vec4(mix(vec3(outline_color), interior_color, final_outline), solid_alpha);
}