// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#include "vtkSobelGradientMagnitudePass1FS.h"

const char *vtkSobelGradientMagnitudePass1FS =
"//VTK::System::Dec\n"
"\n"
"\n"
"// Fragment shader used by the first pass of the Sobel filter render pass.\n"
"\n"
"in vec2 tcoordVC;\n"
"uniform sampler2D source;\n"
"uniform float stepSize; // 1/W\n"
"\n"
"// the output of this shader\n"
"//VTK::Output::Dec\n"
"\n"
"void main(void)\n"
"{\n"
"  vec2 offset=vec2(stepSize,0.0);\n"
"  vec4 t1=texture2D(source,tcoordVC-offset);\n"
"  vec4 t2=texture2D(source,tcoordVC);\n"
"  vec4 t3=texture2D(source,tcoordVC+offset);\n"
"\n"
"  // Gx\n"
"\n"
"  // version with unclamped float textures t3-t1 will be in [-1,1]\n"
"//  gl_FragData[0]=t3-t1;\n"
"\n"
"  // version with clamped unchar textures (t3-t1+1)/2 stays in [0,1]\n"
"  gl_FragData[0]=(t3-t1+1.0)/2.0;\n"
"\n"
"  // Gy\n"
"  gl_FragData[1]=(t1+2.0*t2+t3)/4.0;\n"
"}\n"
"";