ClipPlane.cpp

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/*  Visualization Library                                                             */
/*  http://visualizationlibrary.org                                                   */
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/*  Copyright (c) 2005-2020, Michele Bosi                                             */
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#include <vlGraphics/ClipPlane.hpp>

using namespace vl;

//-----------------------------------------------------------------------------
ClipPlane::ClipPlane(real o, vec3 n)
{
  VL_DEBUG_SET_OBJECT_NAME()
  mPlane.setNormal(n);
  mPlane.setOrigin(o);
  mEnabled = true;
}
//-----------------------------------------------------------------------------
ClipPlane::ClipPlane(const vec3& o, const vec3& n)
{
  VL_DEBUG_SET_OBJECT_NAME()
  mPlane.setNormal(n);
  mPlane.setOrigin(dot(o, n));
  mEnabled = true;
}
//-----------------------------------------------------------------------------
void ClipPlane::apply(int index, const Camera* camera, OpenGLContext*) const
{
  VL_CHECK(index>=0 && index<6);

  // we do our own transformations

  if (enabled())
  {
    glEnable(GL_CLIP_PLANE0 + index);

    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();

    glLoadIdentity();

    mat4 mat;
    if ( boundTransform() )
      mat = camera->viewMatrix() * boundTransform()->worldMatrix();

    vec3 pt1 = mPlane.normal() * mPlane.origin();
    vec3 pt2 = mPlane.normal() * mPlane.origin() + mPlane.normal();

    pt1 = mat * pt1;
    pt2 = mat * pt2;

    vec3 n = pt2 - pt1;
    real orig = dot(n, pt1);

#if defined(VL_OPENGL_ES1)
    float equation[] = { n.x(), n.y(), n.z(), -orig };
    glClipPlanef(GL_CLIP_PLANE0 + index, equation);
#else
    double equation[] = { n.x(), n.y(), n.z(), -orig };
    glClipPlane(GL_CLIP_PLANE0 + index, equation);
#endif

    glPopMatrix();
  }
  else
  {
    glDisable(GL_CLIP_PLANE0 + index);
  }
}
//-----------------------------------------------------------------------------