gl-select.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2011-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
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////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include "gl-select.h"
 
namespace octave
{
 
  void
  opengl_selector::apply_pick_matrix (void)
  {
    GLdouble p_matrix[16];
 
    m_glfcns.glGetDoublev (GL_PROJECTION_MATRIX, p_matrix);
    m_glfcns.glMatrixMode (GL_PROJECTION);
    m_glfcns.glLoadIdentity ();
 
    // The following block is equivalent to gluPickMatrix, but we avoid
    // using glu functions so that we can call OpenGL functions through
    // the QOpenGLFunctions class so that the OpenGL implementation may
    // be selected dynamically.
 
    Matrix viewport = get_viewport_scaled ();
 
    if (size > 0)
      {
        m_glfcns.glTranslatef ((viewport(2) - 2 * (xp - viewport(0))) / size,
                               (viewport(3) - 2 * (yp - viewport(1))) / size, 0);
 
        m_glfcns.glScalef (viewport(2) / size, viewport(3) / size, 1.0);
      }
 
    m_glfcns.glMultMatrixd (p_matrix);
    m_glfcns.glMatrixMode (GL_MODELVIEW);
  }
 
  void
  opengl_selector::setup_opengl_transformation (const axes::properties& props)
  {
    opengl_renderer::setup_opengl_transformation (props);
    apply_pick_matrix ();
  }
 
  void
  opengl_selector::init_marker (const std::string& m, double sz, float width)
  {
    opengl_renderer::init_marker (m, sz, width);
    apply_pick_matrix ();
  }
 
# define BUFFER_SIZE 128
 
  graphics_object
  opengl_selector::select (const graphics_object& ax, int x, int y, int flags)
  {
    m_glfcns.glEnable (GL_DEPTH_TEST);
    m_glfcns.glDepthFunc (GL_LEQUAL);
 
    xp = x;
    yp = y;
 
    GLuint select_buffer[BUFFER_SIZE];
 
    m_glfcns.glSelectBuffer (BUFFER_SIZE, select_buffer);
    m_glfcns.glRenderMode (GL_SELECT);
    m_glfcns.glInitNames ();
 
    object_map.clear ();
 
    draw (ax);
 
    int hits = m_glfcns.glRenderMode (GL_RENDER);
    graphics_object obj;
 
    if (hits > 0)
      {
        GLuint current_minZ = 0xffffffff;
        GLuint current_name = 0xffffffff;
 
        for (int i = 0, j = 0; i < hits && j < BUFFER_SIZE-3; i++)
          {
            GLuint n = select_buffer[j++],
                   minZ = select_buffer[j++];
 
            j++; // skip maxZ
            if (((flags & select_last) == 0 && (minZ <= current_minZ))
                || ((flags & select_last) != 0 && (minZ >= current_minZ)))
              {
                bool candidate = true;
                GLuint name =
                  select_buffer[std::min (j + n, GLuint (BUFFER_SIZE)) - 1];
 
                if ((flags & select_ignore_hittest) == 0)
                  {
                    graphics_object go = object_map[name];
 
                    if (! go.get_properties ().is_hittest ())
                      candidate = false;
                  }
 
                if (candidate)
                  {
                    current_minZ = minZ;
                    current_name = name;
                  }
 
                j += n;
              }
            else
              j += n;
          }
 
        if (current_name != 0xffffffff)
          obj = object_map[current_name];
      }
    else if (hits < 0)
      warning ("opengl_selector::select: selection buffer overflow");
 
    object_map.clear ();
 
    return obj;
  }
 
  void
  opengl_selector::draw (const graphics_object& go, bool toplevel)
  {
    GLuint name = object_map.size ();
 
    object_map[name] = go;
    m_glfcns.glPushName (name);
    set_selecting (true);
    opengl_renderer::draw (go, toplevel);
    set_selecting (false);
    m_glfcns.glPopName ();
  }
 
  void
  opengl_selector::fake_text (double x, double y, double z, const Matrix& bbox,
                              bool use_scale)
  {
    ColumnVector xpos, xp1, xp2;
 
    xpos = get_transform ().transform (x, y, z, use_scale);
 
    xp1 = xp2 = xpos;
    xp1(0) += bbox(0);
    xp1(1) -= bbox(1);
    xp2(0) += (bbox(0) + bbox(2));
    xp2(1) -= (bbox(1) + bbox(3));
 
    ColumnVector p1, p2, p3, p4;
 
    p1 = get_transform ().untransform (xp1(0), xp1(1), xp1(2), false);
    p2 = get_transform ().untransform (xp2(0), xp1(1), xp1(2), false);
    p3 = get_transform ().untransform (xp2(0), xp2(1), xp1(2), false);
    p4 = get_transform ().untransform (xp1(0), xp2(1), xp1(2), false);
 
    m_glfcns.glBegin (GL_QUADS);
    m_glfcns.glVertex3dv (p1.data ());
    m_glfcns.glVertex3dv (p2.data ());
    m_glfcns.glVertex3dv (p3.data ());
    m_glfcns.glVertex3dv (p4.data ());
    m_glfcns.glEnd ();
  }
 
  void
  opengl_selector::draw_text (const text::properties& props)
  {
    if (props.get_string ().isempty ())
      return;
 
    Matrix pos = props.get_data_position ();
    const Matrix bbox = props.get_extent_matrix ();
 
    fake_text (pos(0), pos(1), pos.numel () > 2 ? pos(2) : 0.0, bbox);
  }
 
  Matrix
  opengl_selector::render_text (const std::string& txt,
                                double x, double y, double z,
                                int halign, int valign, double rotation)
  {
    uint8NDArray pixels;
    Matrix bbox (1, 4, 0.0);
 
    // FIXME: probably more efficient to only compute bbox instead
    //        of doing full text rendering...
    text_to_pixels (txt, pixels, bbox, halign, valign, rotation);
    fake_text (x, y, z, bbox, false);
 
    return bbox;
  }
 
  void
  opengl_selector::draw_image (const image::properties& props)
  {
    Matrix xd = props.get_xdata ().matrix_value ();
    octave_idx_type nc = props.get_cdata ().columns ();
    double x_pix_size = (nc == 1 ? 1 : (xd(1) - xd(0)) / (nc - 1));
 
    Matrix yd = props.get_ydata ().matrix_value ();
    octave_idx_type nr = props.get_cdata ().rows ();
    double y_pix_size = (nr == 1 ? 1 : (yd(1) - yd(0)) / (nr - 1));
 
    ColumnVector p1(3, 0.0), p2(3, 0.0), p3(3, 0.0), p4(3, 0.0);
    p1(0) = xd(0) - x_pix_size/2;
    p1(1) = yd(0) - y_pix_size/2;
 
    p2(0) = xd(1) + x_pix_size/2;
    p2(1) = yd(0) - y_pix_size/2;
 
    p3(0) = xd(1) + x_pix_size/2;
    p3(1) = yd(1) + y_pix_size/2;
 
    p4(0) = xd(0) - x_pix_size/2;
    p4(1) = yd(1) + y_pix_size/2;
 
    m_glfcns.glBegin (GL_QUADS);
    m_glfcns.glVertex3dv (p1.data ());
    m_glfcns.glVertex3dv (p2.data ());
    m_glfcns.glVertex3dv (p3.data ());
    m_glfcns.glVertex3dv (p4.data ());
    m_glfcns.glEnd ();
  }
 
}