transform_LookAt.cpp

Go to the documentation of this file.

#include "transform_LookAt.hpp"
#include "opengl.hpp"

LookAt::LookAt()
{
  identity(mTransform);
  identity(mInverse);
}

void LookAt::computeVectors()
{
  Vec3d f = mCenter - mEye;
  mForward = makeNormal( f );
  mUp      = makeNormal(mUp);
  mSide    = makeCross(mForward,mUp);
}

void LookAt::computeTransform()
{
  computeVectors();
  
  mTransform(0,0) =  mSide[0];
  mTransform(0,1) =  mSide[1];
  mTransform(0,2) =  mSide[2];
  mTransform(1,0) =  mUp[0];
  mTransform(1,1) =  mUp[1];
  mTransform(1,2) =  mUp[2];
  mTransform(2,0) = -mForward[0];
  mTransform(2,1) = -mForward[1];
  mTransform(2,2) = -mForward[2];

  mTransform(0,3) = -mEye[0]*    mSide[0] + -mEye[1]*    mSide[1] + -mEye[2]*    mSide[2];
  mTransform(1,3) = -mEye[0]*      mUp[0] + -mEye[1]*      mUp[1] + -mEye[2]*      mUp[2];
  mTransform(2,3) = -mEye[0]*-mForward[0] + -mEye[1]*-mForward[1] + -mEye[2]*-mForward[2];  
}

void LookAt::computeInverse()
{
  computeVectors();

  mInverse(0,0) =  mSide[0];
  mInverse(1,0) =  mSide[1];
  mInverse(2,0) =  mSide[2];
  mInverse(0,1) =  mUp[0];
  mInverse(1,1) =  mUp[1];
  mInverse(2,1) =  mUp[2];
  mInverse(0,2) = -mForward[0];
  mInverse(1,2) = -mForward[1];
  mInverse(2,2) = -mForward[2];

  mInverse(0,3) = mEye[0]*mSide[0] + mEye[1]*mUp[0] + mEye[2]*-mForward[0];
  mInverse(1,3) = mEye[0]*mSide[1] + mEye[1]*mUp[1] + mEye[2]*-mForward[1];
  mInverse(2,3) = mEye[0]*mSide[2] + mEye[1]*mUp[2] + mEye[2]*-mForward[2];
}

void LookAt::computeTransformGL()
{
  glPushAttrib(GL_TRANSFORM_BIT);
  glMatrixMode(GL_MODELVIEW);
  glPushMatrix();
  glLoadIdentity();
  gluLookAt(mEye[0],mEye[1],mEye[2],mCenter[0],mCenter[1],mCenter[2],mUp[0],mUp[1],mUp[2]);
  glGetDoublev(GL_MODELVIEW_MATRIX, &mTransform(0,0) );  
  glPopMatrix();
  glPopAttrib();
}