24 lines
522 B
Plaintext
24 lines
522 B
Plaintext
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precision mediump float;
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uniform vec4 u_Color;
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varying vec4 v_Position;
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void main(){
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// Default alpha is 0
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float alpha = 0.0;
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// Radius is 0.5, since the diameter of our quad is 1
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float radius = 0.5;
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// Get the distance squared of from (0, 0)
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float dist_sq = v_Position.x*v_Position.x + v_Position.y*v_Position.y;
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if(dist_sq < radius*radius){
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// Multiply by 4, since distance squared is at most 0.25
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alpha = 4.0*dist_sq;
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}
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// Use the alpha value in our color
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gl_FragColor = vec4(u_Color.rgb, alpha);
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}
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