DEM.cpp

   1 /***********************************************************************
   2 DEM - Class to represent digital elevation models (DEMs) as float-valued
   3 texture objects.
   4 Copyright (c) 2013-2016 Oliver Kreylos
   5
   6 This file is part of the Augmented Reality Sandbox (SARndbox).
   7
   8 The Augmented Reality Sandbox is free software; you can redistribute it
   9 and/or modify it under the terms of the GNU General Public License as
  10 published by the Free Software Foundation; either version 2 of the
  11 License, or (at your option) any later version.
  12
  13 The Augmented Reality Sandbox is distributed in the hope that it will be
  14 useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with the Augmented Reality Sandbox; if not, write to the Free Software
  20 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  21 ***********************************************************************/
  22
  23 #include "DEM.h"
  24
  25 #include <IO/File.h>
  26 #include <IO/OpenFile.h>
  27 #include <GL/gl.h>
  28 #include <GL/GLContextData.h>
  29 #include <GL/Extensions/GLARBTextureFloat.h>
  30 #include <GL/Extensions/GLARBTextureRectangle.h>
  31 #include <GL/Extensions/GLARBTextureRg.h>
  32 #include <GL/Extensions/GLARBShaderObjects.h>
  33 #include <Geometry/Matrix.h>
  34
  35 /******************************
  36 Methods of class DEM::DataItem:
  37 ******************************/
  38
  39 DEM::DataItem::DataItem(void)
  40     : textureObjectId(0) {
  41     /* Check for and initialize all required OpenGL extensions: */
  42     GLARBTextureFloat::initExtension();
  43     GLARBTextureRectangle::initExtension();
  44     GLARBTextureRg::initExtension();
  45     GLARBShaderObjects::initExtension();
  46
  47     /* Create the texture object: */
  48     glGenTextures(1, &textureObjectId);
  49 }
  50
  51 DEM::DataItem::~DataItem(void) {
  52     /* Destroy the texture object: */
  53     glDeleteTextures(1, &textureObjectId);
  54 }
  55
  56 /********************
  57 Methods of class DEM:
  58 ********************/
  59
  60 void DEM::calcMatrix(void) {
  61     /* Convert the DEM transformation into a projective transformation matrix: */
  62     demTransform = PTransform(transform);
  63     PTransform::Matrix& dtm = demTransform.getMatrix();
  64
  65     /* Pre-multiply the projective transformation matrix with the DEM space to DEM pixel space transformation: */
  66     PTransform dem;
  67     dem.getMatrix()(0, 0) = Scalar(demSize[0] - 1) / (demBox[2] - demBox[0]);
  68     dem.getMatrix()(0, 3) = Scalar(0.5) - Scalar(demSize[0] - 1) / (demBox[2] - demBox[0]) * demBox[0];
  69     dem.getMatrix()(1, 1) = Scalar(demSize[1] - 1) / (demBox[3] - demBox[1]);
  70     dem.getMatrix()(1, 3) = Scalar(0.5) - Scalar(demSize[1] - 1) / (demBox[3] - demBox[1]) * demBox[1];
  71     dem.getMatrix()(2, 2) = Scalar(1) / verticalScale;
  72     dem.getMatrix()(2, 3) = verticalScaleBase - verticalScaleBase / verticalScale;
  73     demTransform.leftMultiply(dem);
  74
  75     /* Convert the full transformation to column-major OpenGL format: */
  76     GLfloat* dtmPtr = demTransformMatrix;
  77     for(int j = 0; j < 4; ++j)
  78         for(int i = 0; i < 4; ++i, ++dtmPtr)
  79             *dtmPtr = GLfloat(dtm(i, j));
  80 }
  81
  82 DEM::DEM(void)
  83     : dem(0),
  84       transform(OGTransform::identity),
  85       verticalScale(1), verticalScaleBase(0) {
  86     demSize[0] = demSize[1] = 0;
  87 }
  88
  89 DEM::~DEM(void) {
  90     delete[] dem;
  91 }
  92
  93 void DEM::initContext(GLContextData& contextData) const {
  94     /* Create and register a data item: */
  95     DataItem* dataItem = new DataItem;
  96     contextData.addDataItem(this, dataItem);
  97
  98     /* Upload the DEM array into the texture object: */
  99     glBindTexture(GL_TEXTURE_RECTANGLE_ARB, dataItem->textureObjectId);
 100     glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 101     glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 102     glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP);
 103     glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP);
 104     glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_LUMINANCE32F_ARB, demSize[0], demSize[1], 0,
 105                  GL_LUMINANCE, GL_FLOAT, dem);
 106     glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0);
 107 }
 108
 109 void DEM::load(const char* demFileName) {
 110     /* Read the DEM file: */
 111     IO::FilePtr demFile = IO::openFile(demFileName);
 112     demFile->setEndianness(Misc::LittleEndian);
 113     demFile->read<int>(demSize, 2);
 114     dem = new float[demSize[1]*demSize[0]];
 115     for(int i = 0; i < 4; ++i)
 116         demBox[i] = double(demFile->read<float>());
 117     demFile->read<float>(dem, demSize[1]*demSize[0]);
 118
 119     /* Update the DEM transformation: */
 120     calcMatrix();
 121 }
 122
 123 float DEM::calcAverageElevation(void) const {
 124     /* Sum all elevation measurements: */
 125     double elevSum = 0.0;
 126     const float* demPtr = dem;
 127     for(int i = demSize[1] * demSize[0]; i > 0; --i, ++demPtr)
 128         elevSum += double(*demPtr);
 129
 130     /* Return the average elevation: */
 131     return float(elevSum / double(demSize[1] * demSize[0]));
 132 }
 133
 134 void DEM::setTransform(const OGTransform& newTransform, Scalar newVerticalScale,
 135                        Scalar newVerticalScaleBase) {
 136     transform = newTransform;
 137     verticalScale = newVerticalScale;
 138     verticalScaleBase = newVerticalScaleBase;
 139
 140     /* Update the DEM transformation: */
 141     calcMatrix();
 142 }
 143
 144 void DEM::bindTexture(GLContextData& contextData) const {
 145     /* Get the context data item: */
 146     DataItem* dataItem = contextData.retrieveDataItem<DataItem>(this);
 147
 148     /* Bind the DEM texture: */
 149     glBindTexture(GL_TEXTURE_RECTANGLE_ARB, dataItem->textureObjectId);
 150 }
 151
 152 void DEM::uploadDemTransform(GLint location) const {
 153     /* Upload the matrix to OpenGL: */
 154     glUniformMatrix4fvARB(location, 1, GL_FALSE, demTransformMatrix);
 155 }