Artifacts in BitmapExpression

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rrTea
Posts: 475
Joined: Sat Feb 15, 2014 9:54 am

Artifacts in BitmapExpression

Post by rrTea »

I get some really strange artifacts in the bitmap that shift even when I change a comment of the component. Here is an example:

Code: Select all

<?xml version="1.0" encoding="iso-8859-1" ?> 
<ZApplication Name="App" Caption="ZGameEditor application" ClearColor="0.4902 0.8745 1 1" FrameRateStyle="2" FixedFrameRate="60" Camera="ProjectionFrontal" NoSound="1"> 
  <OnLoaded> 
    <ZLibrary Comment="HSV Library"> 
      <Source> 
<![CDATA[// 

float angle(float X) 
{ 
  if(X >= 0 && X < 360)return X; 
  if(X > 360)return X-floor(X/360)* 360; 
  if(X <   0)return X+floor(X/360)*-360; 
} 

// 

void hsv(float H, float S, float V) 
{ 
  float R,G,B,I,F,P,Q,T; 

  H = angle(H); 
  S = clamp(S,0,100); 
  V = clamp(V,0,100); 

  H /= 60; 
  S /= 100; 
  V /= 100; 

  if(S == 0) 
  { 
    Color[0] = V; 
    Color[1] = V; 
    Color[2] = V; 
    return; 
  } 

  I = floor(H); 
  F = H-I; 

  P = V*(1-S); 
  Q = V*(1-S*F); 
  T = V*(1-S*(1-F)); 

  if(I == 0){R = V; G = T; B = P;} 
  if(I == 1){R = Q; G = V; B = P;} 
  if(I == 2){R = P; G = V; B = T;} 
  if(I == 3){R = P; G = Q; B = V;} 
  if(I == 4){R = T; G = P; B = V;} 
  if(I == 5){R = V; G = P; B = Q;} 

  Color[0] = R; 
  Color[1] = G; 
  Color[2] = B; 
}]]> 
      </Source> 
    </ZLibrary> 
    <ZExpression> 
      <Expression> 
<![CDATA[Stretch.Scale.X = 2f*App.ViewportWidth/App.ViewportHeight; 
Stretch.Scale.Y = 2;]]> 
      </Expression> 
    </ZExpression> 
  </OnLoaded> 
  <OnRender> 
    <UseMaterial Material="ColorRainbow"/> 
    <RenderTransformGroup Name="Stretch"> 
      <Children> 
        <RenderNet XCount="8"/> 
      </Children> 
    </RenderTransformGroup> 
  </OnRender> 
  <Content> 
    <Material Name="ColorRainbow" Shading="1" Color="1 1 1 0.8993" Light="0"> 
      <Textures> 
        <MaterialTexture Texture="Rainbow" TextureWrapMode="2" TexCoords="1"/> 
      </Textures> 
    </Material> 
    <Mesh Name="PlaneRectangle"> 
      <Producers> 
        <MeshBox/> 
      </Producers> 
    </Mesh> 
    <Array Name="Color" SizeDim1="3"/> 
    <Camera Name="ProjectionFrontal" Comment="No rotation, for interface etc" Kind="1" Position="0 0 10"/> 
    <Bitmap Name="Rainbow" Comment="ff" Width="0" Height="0" Filter="1"> 
      <Producers> 
        <BitmapExpression> 
          <Expression> 
<![CDATA[//X,Y : current coordinate (0..1) 
//Pixel : current color (rgb) 
//Sample expression: Pixel.R=abs(sin(X*16)); 

hsv((X+0.5)*360f,100,100); 
Pixel.R = Color[0]; 
Pixel.G = Color[1]; 
Pixel.B = Color[2];]]> 
          </Expression> 
        </BitmapExpression> 
      </Producers> 
    </Bitmap> 
  </Content> 
</ZApplication> 
...try to change the comment (not any code!) of the component and the preview will shift etc.
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Don't change any code, just type in a new comment...
rainbow artifacts1.png (993 Bytes) Viewed 15281 times
...and the artifacts will shift around.
...and the artifacts will shift around.
rainbow artifacts2.png (1.05 KiB) Viewed 15281 times
User avatar
VilleK
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Posts: 2274
Joined: Mon Jan 15, 2007 4:50 pm
Location: Stockholm, Sweden
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Post by VilleK »

Hi,

This is because of BitmapExpression is threaded :). It calculates several pixels in multiple threads simultaneously. So it doesn't work well with the hsv function that returns value in global variable. Remove the Color variable and change the hsv function to return a vec3 instead, that will make it work.
User avatar
rrTea
Posts: 475
Joined: Sat Feb 15, 2014 9:54 am

Post by rrTea »

I see, that's how it's meant to be used with newer (post-threading) builds. Thanks and sorry for the false alarm :)
User avatar
Kjell
Posts: 1876
Joined: Sat Feb 23, 2008 11:15 pm

Post by Kjell »

:!:

Here you go ( got rid of the angle function too ) ..

Code: Select all

vec3 hsv(float h, float s, float v)
{
  s = clamp(s/100, 0, 1);
  v = clamp(v/100, 0, 1);

  if(!s)return vector3(v, v, v);

  h = h < 0 ? frac(1-abs(frac(h/360)))*6 : frac(h/360)*6;

  float c, f, p, q, t;

  c = floor(h);
  f = h-c;

  p = v*(1-s);
  q = v*(1-s*f);
  t = v*(1-s*(1-f));

  switch(c)
  {
    case 0: return vector3(v, t, p);
    case 1: return vector3(q, v, p);
    case 2: return vector3(p, v, t);
    case 3: return vector3(p, q, v);
    case 4: return vector3(t, p, v);
    case 5: return vector3(v, p, q);
  }
}
K
User avatar
VilleK
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Posts: 2274
Joined: Mon Jan 15, 2007 4:50 pm
Location: Stockholm, Sweden
Contact:

Post by VilleK »

Thanks Kjell, I'll update library.xml with this version.
User avatar
rrTea
Posts: 475
Joined: Sat Feb 15, 2014 9:54 am

Post by rrTea »

Thanks, I also updated the post from earlier today where this library was used (which was unaffected, but just so it's up to date). (1)
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