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1
Question by Saulotti · Aug 01, 2014 at 06:50 AM · shadershader programming

Optmizing per pixel shader (replace color per pixel)

Hey guys,

I need a per pixel shader to:

  1. hide the yellow pixels, or, paint the yellow pixels with alpha = 0;

  2. set the input color to all pink pixels;

  3. set the input color * 65% to all red pixels;

But I think it's to expensive, and some onboard graphic cards are not running very good. I think there is not much registers to run it smooth. Could any one help me in this matter? Here is the code...

 fixed4 frag (v2f i) : COLOR
 {
     fixed4 col = tex2D(_MainTex, i.texcoord); // get texture
     fixed k = (col.r*100) + (col.g*10) + col.b; // pick pixel color
                 
     i.color.a *= ceil(col.a) * ceil(abs(k-110)/110.0); // 0 alpha if yellow
     fixed b1 = ceil(col.a) * ceil(abs(k-100)/100.0); // 0 if red
     fixed b2 = ceil(col.a) * ceil(abs(k-101)/101.0); // 0 if pink
                 
     fixed4 red = fixed4(i.color.r * 0.65, i.color.g * 0.65, i.color.b * 0.65, i.color.a) * (1-b1);
     fixed4 pink = i.color * (1-b2);
     fixed4 tex = ((1,1,1,i.color.a)*col*b1*b2);
                 
     return red + pink + tex;
 }



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avatar image tanoshimi · Aug 01, 2014 at 11:57 AM 0
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Why does this need to be done at runtime? The changes you describe don't seem to be parameterised, so could you not edit your texture in, say, GI$$anonymous$$P and save a modified texture?

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