@kitware/vtk.js/Rendering/OpenGL/SurfaceLIC/glsl/vtkLineIntegralConvolution2D_LIC0.glsl.js

Visualization Toolkit for the Web

var vtkLineIntegralConvolution2D_LIC0 = "//VTK::System::Dec\n\n//=========================================================================\n//\n//  Program:   Visualization Toolkit\n//  Module:    vtkLineIntegralConvolution2D_LIC0.glsl\n//\n//  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen\n//  All rights reserved.\n//  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.\n//\n//     This software is distributed WITHOUT ANY WARRANTY; without even\n//     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR\n//     PURPOSE.  See the above copyright notice for more information.\n//\n//=========================================================================\n\n/**\nThis shader initializes the convolution for the LIC computation.\n*/\n\n// the output of this shader\nlayout(location = 0) out vec4 LICOutput;\nlayout(location = 1) out vec4 SeedOutput;\n\nuniform sampler2D texMaskVectors;\nuniform sampler2D texNoise;\nuniform sampler2D texLIC;\n\nuniform int   uStepNo;         // in step 0 initialize lic and seeds, else just seeds\nuniform int   uPassNo;         // in pass 1 hpf of pass 0 is convolved.\nuniform float uMaskThreshold;  // if |V| < uMaskThreshold render transparent\nuniform vec2  uNoiseBoundsPt1; // tc of upper right pt of noise texture\n\nin vec2 tcoordVC;\n\n// convert from vector coordinate space to noise coordinate space.\n// the noise texture is tiled across the *whole* domain\nvec2 VectorTCToNoiseTC(vec2 vectc)\n{\n  return vectc/uNoiseBoundsPt1;\n}\n\n// get the texture coordidnate to lookup noise value. this\n// depends on the pass number.\nvec2 getNoiseTC(vec2 vectc)\n{\n  // in pass 1 : convert from vector tc to noise tc\n  // in pass 2 : use vector tc\n  if (uPassNo == 0)\n    {\n    return VectorTCToNoiseTC(vectc);\n    }\n  else\n    {\n    return vectc;\n    }\n}\n\n// look up noise value at the given location. The location\n// is supplied in vector texture coordinates, hence the\n// need to convert to noise texture coordinates.\nfloat getNoise(vec2 vectc)\n{\n  return texture2D(texNoise, getNoiseTC(vectc)).r;\n}\n\nvoid main(void)\n{\n  vec2 vectc = tcoordVC.st;\n\n  // lic => (convolution, mask, 0, step count)\n  if (uStepNo == 0)\n    {\n    float maskCriteria = length(texture2D(texMaskVectors, vectc).xyz);\n    float maskFlag;\n    if (maskCriteria <= uMaskThreshold)\n      {\n      maskFlag = 1.0;\n      }\n    else\n      {\n      maskFlag = 0.0;\n      }\n    float noise = getNoise(vectc);\n    LICOutput = vec4(noise, maskFlag, 0.0, 1.0);\n    }\n  else\n    {\n    LICOutput = texture2D(texLIC, vectc);\n    }\n\n  // initial seed\n  SeedOutput = vec4(vectc, 0.0, 1.0);\n}\n";

export { vtkLineIntegralConvolution2D_LIC0 as v };