Serious-Engine/Sources/Engine/Math/Projection_Isometric.cpp

/* Copyright (c) 2002-2012 Croteam Ltd. 
This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License as published by
the Free Software Foundation


This program 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 this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */

#include "Engine/StdH.h"

#include <Engine/Math/Projection.h>

#include <Engine/Math/TextureMapping.h>
#include <Engine/Math/OBBox.h>

#include <Engine/Math/Geometry.inl>
#include <Engine/Math/Clipping.inl>

/////////////////////////////////////////////////////////////////////
//  CIsometricProjection3D

/*
 * Prepare for projecting.
 */
void CIsometricProjection3D::Prepare(void)
{
  FLOATmatrix3D t3dObjectStretch;   // matrix for object stretch
  FLOATmatrix3D t3dObjectRotation;  // matrix for object angles

  // calc. matrices for viewer and object angles and stretch
  MakeRotationMatrix(t3dObjectRotation, pr_ObjectPlacement.pl_OrientationAngle);  // object normally
  MakeInverseRotationMatrix(pr_ViewerRotationMatrix, pr_ViewerPlacement.pl_OrientationAngle);  // viewer inverse
  t3dObjectStretch.Diagonal(pr_ObjectStretch);
  pr_vViewerPosition = pr_ViewerPlacement.pl_PositionVector;
  BOOL bXInverted = pr_ObjectStretch(1)<0;
  BOOL bYInverted = pr_ObjectStretch(2)<0;
  BOOL bZInverted = pr_ObjectStretch(3)<0;

  pr_bInverted = bXInverted!=bYInverted!=bZInverted;

  // if the projection is mirrored
  if (pr_bMirror) {
    // reflect viewer
    ReflectPositionVectorByPlane(pr_plMirror, pr_vViewerPosition);
    ReflectRotationMatrixByPlane_rows(pr_plMirror, pr_ViewerRotationMatrix);
    // invert inversion
    pr_bInverted = !pr_bInverted;
  }

  // calculate screen center
  pr_ScreenCenter = pr_ScreenBBox.Center();

  // if the object is face-forward
  if (pr_bFaceForward) {
    // if it turns only heading
    if (pr_bHalfFaceForward) {
      // get the y-axis vector of object rotation
      FLOAT3D vY(t3dObjectRotation(1,2), t3dObjectRotation(2,2), t3dObjectRotation(3,2));
      // find z axis of viewer
      FLOAT3D vViewerZ(
        pr_ViewerRotationMatrix(3,1),
        pr_ViewerRotationMatrix(3,2),
        pr_ViewerRotationMatrix(3,3));
      // calculate x and z axis vectors to make object head towards viewer
      FLOAT3D vX = (-vViewerZ)*vY;
      vX.Normalize();
      FLOAT3D vZ = vY*vX;
      // compose the rotation matrix back from those angles
      t3dObjectRotation(1,1) = vX(1); t3dObjectRotation(1,2) = vY(1); t3dObjectRotation(1,3) = vZ(1);
      t3dObjectRotation(2,1) = vX(2); t3dObjectRotation(2,2) = vY(2); t3dObjectRotation(2,3) = vZ(2);
      t3dObjectRotation(3,1) = vX(3); t3dObjectRotation(3,2) = vY(3); t3dObjectRotation(3,3) = vZ(3);

      // first apply object stretch then object rotation and then viewer rotation
      pr_mDirectionRotation = pr_ViewerRotationMatrix*t3dObjectRotation;
      pr_RotationMatrix = pr_mDirectionRotation*t3dObjectStretch;
    // if it is fully face forward
    } else {
      // apply object stretch only
      pr_mDirectionRotation.Diagonal(1);
      pr_RotationMatrix = t3dObjectStretch;
    }
  } else {
    // first apply object stretch then object rotation and then viewer rotation
    pr_mDirectionRotation = pr_ViewerRotationMatrix*t3dObjectRotation;
    pr_RotationMatrix = pr_mDirectionRotation*t3dObjectStretch;
  }

  // make clip planes
  MakeClipPlane(FLOAT3D(+ipr_ZoomFactor,0,0), pr_ScreenBBox.Min()(1)-pr_ScreenCenter(1), pr_plClipL);
  MakeClipPlane(FLOAT3D(-ipr_ZoomFactor,0,0), pr_ScreenCenter(1)-pr_ScreenBBox.Max()(1), pr_plClipR);
  MakeClipPlane(FLOAT3D(0,-ipr_ZoomFactor,0), pr_ScreenBBox.Min()(2)-pr_ScreenCenter(2), pr_plClipU);
  MakeClipPlane(FLOAT3D(0,+ipr_ZoomFactor,0), pr_ScreenCenter(2)-pr_ScreenBBox.Max()(2), pr_plClipD);

  // calc. offset of object from viewer
  pr_TranslationVector = pr_ObjectPlacement.pl_PositionVector - pr_vViewerPosition;
  // rotate offset only by viewer angles
  pr_TranslationVector = pr_TranslationVector*pr_ViewerRotationMatrix;
  // transform handle from object space to viewer space and add it to the offset
  pr_TranslationVector -= pr_vObjectHandle*pr_RotationMatrix;

  // mark as prepared
  pr_Prepared = TRUE;
  // calculate constant value used for calculating z-buffer k-value from vertex's z coordinate
  pr_fDepthBufferFactor = -pr_NearClipDistance;
  pr_fDepthBufferMul = (pr_fDepthBufferFar-pr_fDepthBufferNear);
  pr_fDepthBufferAdd = pr_fDepthBufferNear;
}

/*
 * Project 3D object point into 3D view space, before clipping.
 */
void CIsometricProjection3D::PreClip(const FLOAT3D &v3dObjectPoint,
                                       FLOAT3D &v3dTransformedPoint) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  // rotate and translate the point
  v3dTransformedPoint = v3dObjectPoint*pr_RotationMatrix + pr_TranslationVector;
}

/*
 * Project 3D object point into 3D view space, after clipping.
 */                                    
void CIsometricProjection3D::PostClip( const FLOAT3D &v3dTransformedPoint,
                                       FLOAT3D &v3dViewPoint) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);
  // multiply X and Y coordinates with zoom factor and add the center of screen
  v3dViewPoint(1) = pr_ScreenCenter(1) + v3dTransformedPoint(1) * ipr_ZoomFactor*pr_fViewStretch;
  v3dViewPoint(2) = pr_ScreenCenter(2) - v3dTransformedPoint(2) * ipr_ZoomFactor*pr_fViewStretch;
}


void CIsometricProjection3D::PostClip( const FLOAT3D &v3dTransformedPoint, FLOAT fTransformedR,
                                       FLOAT3D &v3dViewPoint, FLOAT &fViewR) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);
  // multiply X and Y coordinates with zoom factor and add the center of screen
  v3dViewPoint(1) = pr_ScreenCenter(1) + v3dTransformedPoint(1) * ipr_ZoomFactor*pr_fViewStretch;
  v3dViewPoint(2) = pr_ScreenCenter(2) - v3dTransformedPoint(2) * ipr_ZoomFactor*pr_fViewStretch;
  fViewR = fTransformedR*ipr_ZoomFactor*pr_fViewStretch;
}


/* Test if a sphere in view space is inside view frustum. */
INDEX CIsometricProjection3D::TestSphereToFrustum(const FLOAT3D &vViewPoint, FLOAT fRadius) const
{
  ASSERT( pr_Prepared && fRadius>=0);
  const FLOAT fX = vViewPoint(1);
  const FLOAT fY = vViewPoint(2);
  const FLOAT fZ = vViewPoint(3);
  INDEX iPass = 1;

  // check to near
  if( fZ-fRadius>-pr_NearClipDistance) {
    return -1;
  } else if( fZ+fRadius>-pr_NearClipDistance) {
    iPass = 0;
  }
  // check to far
  if( pr_FarClipDistance>0) {
    if( fZ+fRadius<-pr_FarClipDistance) {
      return -1;
    } else if( fZ-fRadius<-pr_FarClipDistance) {
      iPass = 0;
    }
  }
  // check to left
  FLOAT fL = fX*pr_plClipL(1) - pr_plClipL.Distance();
  if( fL<-fRadius) {
    return -1;
  } else if( fL<fRadius) {
    iPass = 0;
  }
  // check to right
  FLOAT fR = fX*pr_plClipR(1) - pr_plClipR.Distance();
  if( fR<-fRadius) {
    return -1;
  } else if( fR<fRadius) {
    iPass = 0;
  }
  // check to up
  FLOAT fU = fY*pr_plClipU(2) - pr_plClipU.Distance();
  if( fU<-fRadius) {
    return -1;
  } else if( fU<fRadius) {
    iPass = 0;
  }
  // check to down
  FLOAT fD = fY*pr_plClipD(2) - pr_plClipD.Distance();
  if( fD<-fRadius) {
    return -1;
  } else if( fD<fRadius) {
    iPass = 0;
  }
  // all done
  return iPass;
}


/* Test if an oriented box in view space is inside view frustum. */
INDEX CIsometricProjection3D::TestBoxToFrustum(const FLOATobbox3D &box) const
{
  ASSERT(pr_Prepared);
  INDEX iPass = 1;
  INDEX iTest;

  // check to near
  iTest = (INDEX) box.TestAgainstPlane(FLOATplane3D(FLOAT3D(0,0,-1), pr_NearClipDistance));
  if( iTest<0) {
    return -1;
  } else if( iTest==0) {
    iPass = 0;
  }
  // check to far
  if( pr_FarClipDistance>0) {
    iTest = (INDEX) box.TestAgainstPlane(FLOATplane3D(FLOAT3D(0,0,1), -pr_FarClipDistance));
    if( iTest<0) {
      return -1;
    } else if( iTest==0) {
      iPass = 0;
    }
  }
  // check to left
  iTest = (INDEX) box.TestAgainstPlane(pr_plClipL);
  if( iTest<0) {
    return -1;
  } else if( iTest==0) {
    iPass = 0;
  }
  // check to right
  iTest = (INDEX) box.TestAgainstPlane(pr_plClipR);
  if( iTest<0) {
    return -1;
  } else if( iTest==0) {
    iPass = 0;
  }
  // check to up
  iTest = (INDEX) box.TestAgainstPlane(pr_plClipU);
  if( iTest<0) {
    return -1;
  } else if( iTest==0) {
    iPass = 0;
  }
  // check to down
  iTest = (INDEX) box.TestAgainstPlane(pr_plClipD);
  if( iTest<0) {
    return -1;
  } else if( iTest==0) {
    iPass = 0;
  }
  // all done
  return iPass;
}

/*
 * Project 3D object point into 3D view space.
 */
void CIsometricProjection3D::ProjectCoordinate(const FLOAT3D &v3dObjectPoint,
                                  FLOAT3D &v3dViewPoint) const
{
  // rotate and translate the point
  v3dViewPoint = v3dObjectPoint*pr_RotationMatrix + pr_TranslationVector;
  // multiply X and Y coordinates with zoom factor and add the center of screen
  v3dViewPoint(1) = pr_ScreenCenter(1) + v3dViewPoint(1) * ipr_ZoomFactor*pr_fViewStretch;
  v3dViewPoint(2) = pr_ScreenCenter(2) + v3dViewPoint(2) * ipr_ZoomFactor*pr_fViewStretch;
}

/*
 * Get a distance of object point from the viewer.
 */
FLOAT CIsometricProjection3D::GetDistance(const FLOAT3D &v3dObjectPoint) const
{
  // get just the z coordinate of the point in viewer space
  return
    v3dObjectPoint(1)*pr_RotationMatrix(3,1)+
    v3dObjectPoint(2)*pr_RotationMatrix(3,2)+
    v3dObjectPoint(3)*pr_RotationMatrix(3,3)+
    pr_TranslationVector(3);
}

/*
 * Project 3D object direction vector into 3D view space.
 */
void CIsometricProjection3D::ProjectDirection(const FLOAT3D &v3dObjectPoint,
                                  FLOAT3D &v3dViewPoint) const
{
  // rotate the direction
  v3dViewPoint = v3dObjectPoint*pr_mDirectionRotation;
}

/*
 * Project 3D object axis aligned bounding box into 3D view space.
 */
void CIsometricProjection3D::ProjectAABBox(const FLOATaabbox3D &boxObject,
                                             FLOATaabbox3D &boxView) const
{
  ASSERTALWAYS( "This is not yet implemented");
}

/*
 * Project 3D object plane into 3D view space.
 */
void CIsometricProjection3D::Project(const FLOATplane3D &p3dObjectPlane,
                                FLOATplane3D &p3dTransformedPlane) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  // rotate and translate the plane
  p3dTransformedPlane = p3dObjectPlane*pr_mDirectionRotation + pr_TranslationVector;
}

/* Calculate plane gradient for a plane in 3D view space. */
void CIsometricProjection3D::MakeOoKGradient(const FLOATplane3D &plViewerPlane, CPlanarGradients &pgOoK) const
{
  //ASSERTALWAYS("Function not supported");
}

/*
 * Clip a line.
 */
ULONG CIsometricProjection3D::ClipLine(FLOAT3D &v3dPoint0, FLOAT3D &v3dPoint1) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  // front clip plane is exactly the viewplane
  //const FLOATplane3D plFrontClip(FLOAT3D(0.0f,0.0f,-1.0f), 0.0f);

  ULONG ulCode0 = LCFVERTEX0(LCF_UNCLIPPED);
  ULONG ulCode1 = LCFVERTEX1(LCF_UNCLIPPED);

  // clip the line by each plane at the time, skip if some removes entire line
  if (ClipLineByNearPlane(v3dPoint0, v3dPoint1, 0.0f,  ulCode0, ulCode1, LCF_NEAR)
  // if something remains
    ) {
    // return the clip code for both vertices
    return ulCode0 | ulCode1;
  // if some of the planes removed entire line
  } else {
    // return the code that tells that entire line is removed
    return LCF_EDGEREMOVED;
  }
}

/*
 * Get placement for a ray through a projected point.
 */
void CIsometricProjection3D::RayThroughPoint(const FLOAT3D &v3dViewPoint,
                                               CPlacement3D &plRay) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  /* The direction in object space is exactly the viewer direction, while
   * the position is back-transformed position of the point from the view plane
   * to object space.
   */

  // just copy the orientation angle
  plRay.pl_OrientationAngle = pr_ViewerPlacement.pl_OrientationAngle;

  // the point on view plane has a view z coordinate of 0
  FLOAT3D vViewPlanePoint;
  vViewPlanePoint(1) = (v3dViewPoint(1)-pr_ScreenCenter(1)) / ipr_ZoomFactor;
  vViewPlanePoint(2) = (v3dViewPoint(2)-pr_ScreenCenter(2)) / ipr_ZoomFactor;
  vViewPlanePoint(3) = 0.0f;
  // back transform the point to get the position vector
  plRay.pl_PositionVector = (vViewPlanePoint-pr_TranslationVector)*!pr_RotationMatrix;
}

/*
 * Check if an object-space plane is visible.
 */
BOOL CIsometricProjection3D::IsObjectPlaneVisible(const FLOATplane3D &p3dObjectPlane) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  // the object plane is visible is it is not heading away from the view plane
  return (p3dObjectPlane*pr_mDirectionRotation)(3)>0.0f;
}

/*
 * Check if a viewer-space plane is visible.
 */
BOOL CIsometricProjection3D::IsViewerPlaneVisible(const FLOATplane3D &p3dViewerPlane) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  // the object plane is visible is it is not heading away from the view plane
  return p3dViewerPlane(3)>0.01f;
}

/*
 * Calculate a mip-factor for a given object.
 */
// by its distance from viewer
FLOAT CIsometricProjection3D::MipFactor(FLOAT fDistance) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  /* calculated using following formula:
  k = log2(1024*z/xratio);
  */
  return Log2(1024.0f/ipr_ZoomFactor);
}
// general mip-factor for target object
FLOAT CIsometricProjection3D::MipFactor(void) const
{
  // check that the projection object is prepared for projecting
  ASSERT(pr_Prepared);

  /* calculated using following formula:
  k = log2(1024*z/xratio);
  */
  return Log2(1024.0f/ipr_ZoomFactor);
}