[gegl] shadows-highlights-correction: Simplify code

[Debarshi Ray <debarshir src gnome org>]

commit 442b2e505e85c6f7185dd1f3feed4f62486605ab
Author: Debarshi Ray <debarshir gnome org>
Date:   Sun Dec 24 14:00:23 2017 +0100

    shadows-highlights-correction: Simplify code
    
    Fallout from 9384338e84d741248541610a6b178dc250a357bb

 opencl/shadows-highlights-correction.cl.h |    8 ++------
 1 files changed, 2 insertions(+), 6 deletions(-)
---
diff --git a/opencl/shadows-highlights-correction.cl.h b/opencl/shadows-highlights-correction.cl.h
index 08ae4b2..5aaff3b 100644
--- a/opencl/shadows-highlights-correction.cl.h
+++ b/opencl/shadows-highlights-correction.cl.h
@@ -9,10 +9,6 @@ static const char* shadows_highlights_correction_cl_source =
 "  /* a contains underlying image; b contains mask */                          \n"
 "                                                                              \n"
 "  const float3 scale = (float3)(100.0f, 128.0f, 128.0f);                      \n"
-"  const float lmax = 1.0f;                                                    \n"
-"  const float halfmax = 0.5f;                                                 \n"
-"  const float doublemax = 2.0f;                                               \n"
-"                                                                              \n"
 "  float3 a = in_a / scale;                                                    \n"
 "  float3 b = in_b / scale;                                                    \n"
 "                                                                              \n"
@@ -22,7 +18,7 @@ static const char* shadows_highlights_correction_cl_source =
 "  while(opacity2 > 0.0f)                                                      \n"
 "  {                                                                           \n"
 "    float la = a.x;                                                           \n"
-"    float lb = (b.x - halfmax) * sign(opacity)*sign(lmax - la) + halfmax;     \n"
+"    float lb = (b.x - 0.5f) * sign(opacity)*sign(1.0f - la) + 0.5f;           \n"
 "    float lref = copysign(fabs(la) > low_approximation ? 1.0f/fabs(la) : 1.0f/low_approximation, la);\n"
 "    float href = copysign(fabs(1.0f - la) > low_approximation ? 1.0f/fabs(1.0f - la) : 
1.0f/low_approximation, 1.0f - la);\n"
 "                                                                              \n"
@@ -30,7 +26,7 @@ static const char* shadows_highlights_correction_cl_source =
 "    float optrans = chunk * transform;                                        \n"
 "    opacity2 -= 1.0f;                                                         \n"
 "                                                                              \n"
-"    a.x = la * (1.0f - optrans) + (la > halfmax ? lmax - (lmax - doublemax * (la - halfmax)) * (lmax-lb) : 
doublemax * la * lb) * optrans;\n"
+"    a.x = la * (1.0f - optrans) + (la > 0.5f ? 1.0f - (1.0f - 2.0f * (la - 0.5f)) * (1.0f-lb) : 2.0f * la * 
lb) * optrans;\n"
 "    a.y = a.y * (1.0f - optrans) + (a.y + b.y) * (a.x*lref * ccorrect + (1.0f - a.x)*href * (1.0f - 
ccorrect)) * optrans;\n"
 "    a.z = a.z * (1.0f - optrans) + (a.z + b.z) * (a.x*lref * ccorrect + (1.0f - a.x)*href * (1.0f - 
ccorrect)) * optrans;\n"
 "  }                                                                           \n"