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++ VARYING vec2 center_vec;
++
++ void MAIN()
++ {
++ float radius = 0.25;
++ float dist_to_center = length(center_vec) / radius;
++ vec2 texcoord = INPUT_UV;
++ if (dist_to_center <= 1.0) {
++ float rotation_amount = (1.0 - dist_to_center) * (1.0 - dist_to_center);
++ float r = radians(360.0) * rotation_amount / 4.0 * FRAMEBUFFER_Y_UP;
++ float cos_r = cos(r);
++ float sin_r = sin(r);
++ mat2 rotation = mat2(cos_r, sin_r, -sin_r, cos_r);
++ texcoord = vec2(0.5, 0.5) + rotation * (INPUT_UV - vec2(0.5, 0.5));
++ }
++ vec4 c = texture(INPUT, texcoord);
++ c.r *= uRed;
++ FRAGCOLOR = c;
++ }