Helper

vtkOpenGLHelper

Store the shaders, program, and ibo in a common place
as they are used together frequently. This is just
a convenience class.

program

The shader program

VAO

The VertexArrayObject

CABO

The cell array buffer object. See vtkCellArrayBufferObject

shaderSourceTime

The last time the shader source code changed

attributeUpdateTime

The last time the attributes for the VAO were assigned

Source

index.js

import macro from 'vtk.js/Sources/macros';
import vtkCellArrayBufferObject from 'vtk.js/Sources/Rendering/OpenGL/CellArrayBufferObject';
import vtkShaderProgram from 'vtk.js/Sources/Rendering/OpenGL/ShaderProgram';
import vtkVertexArrayObject from 'vtk.js/Sources/Rendering/OpenGL/VertexArrayObject';

import { Representation } from 'vtk.js/Sources/Rendering/Core/Property/Constants';

export const primTypes = {
  Start: 0,
  Points: 0,
  Lines: 1,
  Tris: 2,
  TriStrips: 3,
  TrisEdges: 4,
  TriStripsEdges: 5,
  End: 6,
};

// ----------------------------------------------------------------------------
// vtkOpenGLHelper methods
// ----------------------------------------------------------------------------

function vtkOpenGLHelper(publicAPI, model) {
  // Set our className
  model.classHierarchy.push('vtkOpenGLHelper');

  publicAPI.setOpenGLRenderWindow = (win) => {
    model.context = win.getContext();
    model.program.setContext(model.context);
    model.VAO.setOpenGLRenderWindow(win);
    model.CABO.setOpenGLRenderWindow(win);
  };

  publicAPI.releaseGraphicsResources = (oglwin) => {
    model.VAO.releaseGraphicsResources();
    model.CABO.releaseGraphicsResources();
    model.CABO.setElementCount(0);
  };

  publicAPI.drawArrays = (ren, actor, rep, oglMapper) => {
    // Are there any entries
    if (model.CABO.getElementCount()) {
      // are we drawing edges
      const mode = publicAPI.getOpenGLMode(rep);
      const wideLines = publicAPI.haveWideLines(ren, actor);
      const gl = model.context;
      const depthMask = gl.getParameter(gl.DEPTH_WRITEMASK);
      if (model.pointPicking) {
        gl.depthMask(false);
      }
      const drawingLines = mode === gl.LINES;
      if (drawingLines && wideLines) {
        publicAPI.updateShaders(ren, actor, oglMapper);
        gl.drawArraysInstanced(
          mode,
          0,
          model.CABO.getElementCount(),
          2 * Math.ceil(actor.getProperty().getLineWidth())
        );
      } else {
        gl.lineWidth(actor.getProperty().getLineWidth());
        publicAPI.updateShaders(ren, actor, oglMapper);
        gl.drawArrays(mode, 0, model.CABO.getElementCount());
        // reset the line width
        gl.lineWidth(1);
      }
      const stride =
        (mode === gl.POINTS ? 1 : 0) || (mode === gl.LINES ? 2 : 3);
      if (model.pointPicking) {
        gl.depthMask(depthMask);
      }
      return model.CABO.getElementCount() / stride;
    }
    return 0;
  };

  publicAPI.getOpenGLMode = (rep) => {
    if (model.pointPicking) {
      return model.context.POINTS;
    }
    const type = model.primitiveType;
    if (rep === Representation.POINTS || type === primTypes.Points) {
      return model.context.POINTS;
    }
    if (
      rep === Representation.WIREFRAME ||
      type === primTypes.Lines ||
      type === primTypes.TrisEdges ||
      type === primTypes.TriStripsEdges
    ) {
      return model.context.LINES;
    }
    return model.context.TRIANGLES;
  };

  publicAPI.haveWideLines = (ren, actor) => {
    if (actor.getProperty().getLineWidth() > 1.0) {
      // we have wide lines, but the OpenGL implementation may
      // actually support them, check the range to see if we
      // really need have to implement our own wide lines
      if (model.CABO.getOpenGLRenderWindow()) {
        if (
          model.CABO.getOpenGLRenderWindow().getHardwareMaximumLineWidth() >=
          actor.getProperty().getLineWidth()
        ) {
          return false;
        }
      }
      return true;
    }
    return false;
  };

  publicAPI.getNeedToRebuildShaders = (ren, actor, oglMapper) => {
    // has something changed that would require us to recreate the shader?
    // candidates are
    // property modified (representation interpolation and lighting)
    // input modified
    // mapper modified (lighting complexity)
    if (
      oglMapper.getNeedToRebuildShaders(publicAPI, ren, actor) ||
      publicAPI.getProgram() === 0 ||
      publicAPI.getShaderSourceTime().getMTime() < oglMapper.getMTime() ||
      publicAPI.getShaderSourceTime().getMTime() < actor.getMTime()
    ) {
      return true;
    }
    return false;
  };

  publicAPI.updateShaders = (ren, actor, oglMapper) => {
    // has something changed that would require us to recreate the shader?
    if (publicAPI.getNeedToRebuildShaders(ren, actor, oglMapper)) {
      const shaders = { Vertex: null, Fragment: null, Geometry: null };
      oglMapper.buildShaders(shaders, ren, actor);

      // compile and bind the program if needed
      const newShader = model.CABO.getOpenGLRenderWindow()
        .getShaderCache()
        .readyShaderProgramArray(
          shaders.Vertex,
          shaders.Fragment,
          shaders.Geometry
        );

      // if the shader changed reinitialize the VAO
      if (newShader !== publicAPI.getProgram()) {
        publicAPI.setProgram(newShader);
        // reset the VAO as the shader has changed
        publicAPI.getVAO().releaseGraphicsResources();
      }

      publicAPI.getShaderSourceTime().modified();
    } else {
      model.CABO.getOpenGLRenderWindow()
        .getShaderCache()
        .readyShaderProgram(publicAPI.getProgram());
    }

    publicAPI.getVAO().bind();

    oglMapper.setMapperShaderParameters(publicAPI, ren, actor);
    oglMapper.setPropertyShaderParameters(publicAPI, ren, actor);
    oglMapper.setCameraShaderParameters(publicAPI, ren, actor);
    oglMapper.setLightingShaderParameters(publicAPI, ren, actor);

    oglMapper.invokeShaderCallbacks(publicAPI, ren, actor);
  };

  publicAPI.setMapperShaderParameters = (ren, actor, size) => {
    if (publicAPI.haveWideLines(ren, actor)) {
      publicAPI
        .getProgram()
        .setUniform2f('viewportSize', size.usize, size.vsize);
      const lineWidth = parseFloat(actor.getProperty().getLineWidth());
      const halfLineWidth = lineWidth / 2.0;
      publicAPI
        .getProgram()
        .setUniformf('lineWidthStepSize', lineWidth / Math.ceil(lineWidth));
      publicAPI.getProgram().setUniformf('halfLineWidth', halfLineWidth);
    }
    if (
      model.primitiveType === primTypes.Points ||
      actor.getProperty().getRepresentation() === Representation.POINTS
    ) {
      publicAPI
        .getProgram()
        .setUniformf('pointSize', actor.getProperty().getPointSize());
    } else if (model.pointPicking) {
      publicAPI
        .getProgram()
        .setUniformf('pointSize', publicAPI.getPointPickingPrimitiveSize());
    }
  };

  publicAPI.replaceShaderPositionVC = (shaders, ren, actor) => {
    let VSSource = shaders.Vertex;

    // Always set point size in case we need picking
    VSSource = vtkShaderProgram.substitute(VSSource, '//VTK::PositionVC::Dec', [
      '//VTK::PositionVC::Dec',
      'uniform float pointSize;',
    ]).result;
    VSSource = vtkShaderProgram.substitute(
      VSSource,
      '//VTK::PositionVC::Impl',
      ['//VTK::PositionVC::Impl', '  gl_PointSize = pointSize;'],
      false
    ).result;

    // for lines, make sure we add the width code
    if (
      publicAPI.getOpenGLMode(actor.getProperty().getRepresentation()) ===
        model.context.LINES &&
      publicAPI.haveWideLines(ren, actor)
    ) {
      VSSource = vtkShaderProgram.substitute(
        VSSource,
        '//VTK::PositionVC::Dec',
        [
          '//VTK::PositionVC::Dec',
          'uniform vec2 viewportSize;',
          'uniform float lineWidthStepSize;',
          'uniform float halfLineWidth;',
        ]
      ).result;
      VSSource = vtkShaderProgram.substitute(
        VSSource,
        '//VTK::PositionVC::Impl',
        [
          '//VTK::PositionVC::Impl',
          ' if (halfLineWidth > 0.0)',
          '   {',
          '   float offset = float(gl_InstanceID / 2) * lineWidthStepSize - halfLineWidth;',
          '   vec4 tmpPos = gl_Position;',
          '   vec3 tmpPos2 = tmpPos.xyz / tmpPos.w;',
          '   tmpPos2.x = tmpPos2.x + 2.0 * mod(float(gl_InstanceID), 2.0) * offset / viewportSize[0];',
          '   tmpPos2.y = tmpPos2.y + 2.0 * mod(float(gl_InstanceID + 1), 2.0) * offset / viewportSize[1];',
          '   gl_Position = vec4(tmpPos2.xyz * tmpPos.w, tmpPos.w);',
          '   }',
        ]
      ).result;
    }
    shaders.Vertex = VSSource;
  };

  publicAPI.getPointPickingPrimitiveSize = () => {
    if (model.primitiveType === primTypes.Points) {
      return 2;
    }
    if (model.primitiveType === primTypes.Lines) {
      return 4;
    }
    return 6;
  };
}

// ----------------------------------------------------------------------------
// Object factory
// ----------------------------------------------------------------------------

const DEFAULT_VALUES = {
  context: null,
  program: null,
  shaderSourceTime: null,
  VAO: null,
  attributeUpdateTime: null,
  CABO: null,
  primitiveType: 0,
  pointPicking: false,
};

// ----------------------------------------------------------------------------

export function extend(publicAPI, model, initialValues = {}) {
  Object.assign(model, DEFAULT_VALUES, initialValues);

  // Build VTK API
  macro.obj(publicAPI, model);

  model.shaderSourceTime = {};
  macro.obj(model.shaderSourceTime);

  model.attributeUpdateTime = {};
  macro.obj(model.attributeUpdateTime);

  macro.setGet(publicAPI, model, [
    'program',
    'shaderSourceTime',
    'VAO',
    'attributeUpdateTime',
    'CABO',
    'primitiveType',
    'pointPicking',
  ]);

  model.program = vtkShaderProgram.newInstance();
  model.VAO = vtkVertexArrayObject.newInstance();
  model.CABO = vtkCellArrayBufferObject.newInstance();

  // Object methods
  vtkOpenGLHelper(publicAPI, model);
}

// ----------------------------------------------------------------------------

export const newInstance = macro.newInstance(extend);

// ----------------------------------------------------------------------------

export default { newInstance, extend, primTypes };