render/fx_renderer/gles2/shaders/stencil_mask.frag


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#ifdef GL_FRAGMENT_PRECISION_HIGH
precision highp float;
#else
precision mediump float;
#endif

varying vec2 v_texcoord;

uniform vec2 half_size;
uniform vec2 position;
uniform float radius;

void main() {
	vec2 q = abs(gl_FragCoord.xy - position - half_size) - half_size + radius;
	float dist = min(max(q.x,q.y), 0.0) + length(max(q, 0.0)) - radius;
	float smoothedAlpha = 1.0 - smoothstep(-1.0, 0.5, dist);
	gl_FragColor = mix(vec4(0.0), vec4(1.0), smoothedAlpha);

	if (gl_FragColor.a < 1.0) {
		discard;
	}
}