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

const char *vtkCellGridShaderTessellationControl =
"//VTK::System::Dec\n"
"// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen\n"
"// SPDX-License-Identifier: BSD-3-Clause\n"
"\n"
"//VTK::Camera::Dec\n"
"\n"
"layout(vertices = {PatchSize}) out;\n"
"\n"
"flat in int cellIdVSOutput[];\n"
"flat in int sideIdVSOutput[];\n"
"flat in int instanceIdVSOutput[];\n"
"smooth in vec3 pcoordVSOutput[];\n"
"\n"
"patch out int cellIdTCSOutput;\n"
"patch out int sideIdTCSOutput;\n"
"patch out int instanceIdTCSOutput;\n"
"out vec3 pcoordTCSOutput[];\n"
"\n"
"uniform ivec2 tessellation_levels_range;\n"
"uniform float max_distance;\n"
"\n"
"#if {PatchSize} == 2\n"
"void prepareTessellationLevels()\n"
"{{\n"
"  // ----------------------------------------------------------------------\n"
"  int min_tl = tessellation_levels_range[0];\n"
"  int max_tl = tessellation_levels_range[1];\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 1: transform each vertex into eye space\n"
"  vec4 eyeSpacePos0 = MCVCMatrix * gl_in[0].gl_Position;\n"
"  vec4 eyeSpacePos1 = MCVCMatrix * gl_in[1].gl_Position;\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 2: \"distance\" from camera scaled between 0 and 1\n"
"  float distance0 = clamp((abs(eyeSpacePos0.z)) / (max_distance), 0.0f, 1.0f);\n"
"  float distance1 = clamp((abs(eyeSpacePos1.z)) / (max_distance), 0.0f, 1.0f);\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 3: interpolate edge tessellation level based on closer vertex\n"
"  float tessLevel0 = mix(max_tl, min_tl, min(distance1, distance0));\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 4: set the corresponding outer edge tessellation levels\n"
"  gl_TessLevelOuter[0] = 1;\n"
"  gl_TessLevelOuter[1] = tessLevel0;\n"
"}}\n"
"#elif {PatchSize} == 3\n"
"void prepareTessellationLevels()\n"
"{{\n"
"  // ----------------------------------------------------------------------\n"
"  int min_tl = tessellation_levels_range[0];\n"
"  int max_tl = tessellation_levels_range[1];\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 1: transform each vertex into eye space\n"
"  vec4 eyeSpacePos00 = MCVCMatrix * gl_in[0].gl_Position;\n"
"  vec4 eyeSpacePos01 = MCVCMatrix * gl_in[1].gl_Position;\n"
"  vec4 eyeSpacePos11 = MCVCMatrix * gl_in[2].gl_Position;\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 2: \"distance\" from camera scaled between 0 and 1\n"
"  float distance00 = clamp((abs(eyeSpacePos00.z)) / (max_distance), 0.0f, 1.0f);\n"
"  float distance01 = clamp((abs(eyeSpacePos01.z)) / (max_distance), 0.0f, 1.0f);\n"
"  float distance11 = clamp((abs(eyeSpacePos11.z)) / (max_distance), 0.0f, 1.0f);\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 3: interpolate edge tessellation level based on closer vertex\n"
"  float tessLevel0 = mix(max_tl, min_tl, min(distance11, distance00));\n"
"  float tessLevel1 = mix(max_tl, min_tl, min(distance00, distance01));\n"
"  float tessLevel2 = mix(max_tl, min_tl, min(distance01, distance11));\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 4: set the corresponding outer edge tessellation levels\n"
"  gl_TessLevelOuter[0] = tessLevel0;\n"
"  gl_TessLevelOuter[1] = tessLevel1;\n"
"  gl_TessLevelOuter[2] = tessLevel2;\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 5: set the inner tessellation levels to the max of the three edges\n"
"  gl_TessLevelInner[0] = max(tessLevel0, max(tessLevel1, tessLevel2));\n"
"}}\n"
"#elif {PatchSize} == 4\n"
"void prepareTessellationLevels()\n"
"{{\n"
"  // ----------------------------------------------------------------------\n"
"  int min_tl = tessellation_levels_range[0];\n"
"  int max_tl = tessellation_levels_range[1];\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 1: transform each vertex into eye space\n"
"  vec4 eyeSpacePos00 = MCVCMatrix * gl_in[0].gl_Position;\n"
"  vec4 eyeSpacePos01 = MCVCMatrix * gl_in[1].gl_Position;\n"
"  vec4 eyeSpacePos10 = MCVCMatrix * gl_in[2].gl_Position;\n"
"  vec4 eyeSpacePos11 = MCVCMatrix * gl_in[3].gl_Position;\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 2: \"distance\" from camera scaled between 0 and 1\n"
"  float distance00 = clamp((abs(eyeSpacePos00.z)) / (max_distance), 0.0f, 1.0f);\n"
"  float distance01 = clamp((abs(eyeSpacePos01.z)) / (max_distance), 0.0f, 1.0f);\n"
"  float distance10 = clamp((abs(eyeSpacePos10.z)) / (max_distance), 0.0f, 1.0f);\n"
"  float distance11 = clamp((abs(eyeSpacePos11.z)) / (max_distance), 0.0f, 1.0f);\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 3: interpolate edge tessellation level based on closer vertex\n"
"  float tessLevel0 = mix(max_tl, min_tl, min(distance10, distance00));\n"
"  float tessLevel1 = mix(max_tl, min_tl, min(distance00, distance01));\n"
"  float tessLevel2 = mix(max_tl, min_tl, min(distance01, distance11));\n"
"  float tessLevel3 = mix(max_tl, min_tl, min(distance11, distance10));\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 4: set the corresponding outer edge tessellation levels\n"
"  gl_TessLevelOuter[0] = tessLevel0;\n"
"  gl_TessLevelOuter[1] = tessLevel1;\n"
"  gl_TessLevelOuter[2] = tessLevel2;\n"
"  gl_TessLevelOuter[3] = tessLevel3;\n"
"\n"
"  // ----------------------------------------------------------------------\n"
"  // Step 5: set the inner tessellation levels to the max of the two parallel edges\n"
"  gl_TessLevelInner[0] = max(tessLevel1, tessLevel3);\n"
"  gl_TessLevelInner[1] = max(tessLevel0, tessLevel2);\n"
"}}\n"
"#endif\n"
"\n"
"void main()\n"
"{{\n"
"  if (gl_InvocationID == 0)\n"
"  {{\n"
"    prepareTessellationLevels();\n"
"\n"
"    // It's okay to copy only the first value, because all patch vertices come from the same cell/side\n"
"    cellIdTCSOutput = cellIdVSOutput[0];\n"
"    sideIdTCSOutput = sideIdVSOutput[0];\n"
"  }}\n"
"\n"
"  instanceIdTCSOutput = instanceIdVSOutput[gl_InvocationID];\n"
"  gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;\n"
"  pcoordTCSOutput[gl_InvocationID] = pcoordVSOutput[gl_InvocationID];\n"
"}}\n"
"";