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112 lines
4.7 KiB
Common Lisp
112 lines
4.7 KiB
Common Lisp
// Note: "float *scanLine" may be replaced by code with actual input data type
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__kernel void processNineCellWindow( __global float *scanLine1,
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__global float *scanLine2,
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__global float *scanLine3,
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__global uchar4 *resultLine, // This is an image!
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__global float *rasterParams
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)
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{
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// Get the index of the current element
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const int i = get_global_id(0);
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float x11 = scanLine1[i];
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float x12 = scanLine1[i+1];
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float x13 = scanLine1[i+2];
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float x21 = scanLine2[i];
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float x22 = scanLine2[i+1];
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float x23 = scanLine2[i+2];
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float x31 = scanLine3[i];
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float x32 = scanLine3[i+1];
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float x33 = scanLine3[i+2];
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if ( x22 == rasterParams[0] )
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{
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float alpha = rasterParams[8] * rasterParams[16];
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resultLine[i] = (uchar4)(rasterParams[13] * alpha,
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rasterParams[14] * alpha,
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rasterParams[15] * alpha, 255 * alpha);
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}
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else
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{
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if ( x11 == rasterParams[0] ) x11 = x22;
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if ( x12 == rasterParams[0] ) x12 = x22;
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if ( x13 == rasterParams[0] ) x13 = x22;
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if ( x21 == rasterParams[0] ) x21 = x22;
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// Note: skip central cell x22
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if ( x23 == rasterParams[0] ) x23 = x22;
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if ( x31 == rasterParams[0] ) x31 = x22;
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if ( x32 == rasterParams[0] ) x32 = x22;
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if ( x33 == rasterParams[0] ) x33 = x22;
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float derX = ( ( x13 + x23 + x23 + x33 ) - ( x11 + x21 + x21 + x31 ) ) / ( 8.0f * rasterParams[3] );
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float derY = ( ( x31 + x32 + x32 + x33 ) - ( x11 + x12 + x12 + x13 ) ) / ( 8.0f * -rasterParams[4]);
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if ( derX == rasterParams[0] ||
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derX == rasterParams[0] )
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{
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float alpha = rasterParams[5] * rasterParams[16];
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resultLine[i] = (uchar4)(rasterParams[13] * alpha,
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rasterParams[14] * alpha,
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rasterParams[15] * alpha, 255 * alpha);
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}
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else
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{
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float res;
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if ( rasterParams[17] ) // Multi directional?
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{
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// Weighted multi direction as in http://pubs.usgs.gov/of/1992/of92-422/of92-422.pdf
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// Fast formula from GDAL DEM
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const float xx = derX * derX;
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const float yy = derY * derY;
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const float xx_plus_yy = xx + yy;
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// Flat?
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if ( xx_plus_yy == 0.0f )
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{
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res = clamp( 1.0f + rasterParams[9], 0.0f, 255.0f );
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}
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else
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{
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// ... then the shade value from different azimuth
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float val225_mul_127 = rasterParams[10] +
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( derX - derY ) * rasterParams[11];
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val225_mul_127 = ( val225_mul_127 <= 0.0f ) ? 0.0f : val225_mul_127;
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float val270_mul_127 = rasterParams[10] -
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derX * rasterParams[12];
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val270_mul_127 = ( val270_mul_127 <= 0.0f ) ? 0.0f : val270_mul_127;
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float val315_mul_127 = rasterParams[10] +
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( derX + derY ) * rasterParams[11];
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val315_mul_127 = ( val315_mul_127 <= 0.0f ) ? 0.0f : val315_mul_127;
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float val360_mul_127 = rasterParams[10] -
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derY * rasterParams[12];
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val360_mul_127 = ( val360_mul_127 <= 0.0f ) ? 0.0f : val360_mul_127;
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// ... then the weighted shading
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const float weight_225 = 0.5f * xx_plus_yy - derX * derY;
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const float weight_270 = xx;
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const float weight_315 = xx_plus_yy - weight_225;
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const float weight_360 = yy;
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const float cang_mul_127 = (
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( weight_225 * val225_mul_127 +
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weight_270 * val270_mul_127 +
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weight_315 * val315_mul_127 +
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weight_360 * val360_mul_127 ) / xx_plus_yy ) /
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( 1.0f + rasterParams[8] * xx_plus_yy );
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res = clamp( 1.0f + cang_mul_127, 0.0f, 255.0f );
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}
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}
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else
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{
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res = ( rasterParams[9] -
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( derY * rasterParams[6] -
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derX * rasterParams[7] )) /
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sqrt( 1.0f + rasterParams[8] *
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( derX * derX + derY * derY ) );
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res = res <= 0.0f ? 1.0f : 1.0f + res;
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}
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res = res * rasterParams[5];
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resultLine[i] = (uchar4)(res, res, res, 255 * rasterParams[5]);
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}
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}
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}
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