path: root/indra/newview/llviewercamera.cpp

/**
 * @file llviewercamera.cpp
 * @brief LLViewerCamera class implementation
 *
 * $LicenseInfo:firstyear=2002&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#include "llviewerprecompiledheaders.h"

#define LLVIEWERCAMERA_CPP
#include "llviewercamera.h"

// Viewer includes
#include "llagent.h"
#include "llagentcamera.h"
#include "llmatrix4a.h"
#include "llviewercontrol.h"
#include "llviewerobjectlist.h"
#include "llviewerregion.h"
#include "llviewerwindow.h"
#include "llvovolume.h"
#include "llworld.h"
#include "lltoolmgr.h"
#include "llviewerjoystick.h"

// Linden library includes
#include "lldrawable.h"
#include "llface.h"
#include "llgl.h"
#include "llglheaders.h"
#include "llquaternion.h"
#include "llwindow.h"           // getPixelAspectRatio()
#include "lltracerecording.h"
#include "llenvironment.h"

// System includes
#include <iomanip> // for setprecision

LLTrace::CountStatHandle<> LLViewerCamera::sVelocityStat("camera_velocity");
LLTrace::CountStatHandle<> LLViewerCamera::sAngularVelocityStat("camera_angular_velocity");

LLViewerCamera::eCameraID LLViewerCamera::sCurCameraID = LLViewerCamera::CAMERA_WORLD;

//glu pick matrix implementation borrowed from Mesa3D
glh::matrix4f gl_pick_matrix(GLfloat x, GLfloat y, GLfloat width, GLfloat height, GLint* viewport)
{
    GLfloat m[16];
    GLfloat sx, sy;
    GLfloat tx, ty;

    sx = viewport[2] / width;
    sy = viewport[3] / height;
    tx = (viewport[2] + 2.f * (viewport[0] - x)) / width;
    ty = (viewport[3] + 2.f * (viewport[1] - y)) / height;

    #define M(row,col) m[col*4+row]
    M(0,0) = sx; M(0,1) = 0.f; M(0,2) = 0.f; M(0,3) = tx;
    M(1,0) = 0.f; M(1,1) = sy; M(1,2) = 0.f; M(1,3) = ty;
    M(2,0) = 0.f; M(2,1) = 0.f; M(2,2) = 1.f; M(2,3) = 0.f;
    M(3,0) = 0.f; M(3,1) = 0.f; M(3,2) = 0.f; M(3,3) = 1.f;
    #undef M

    return glh::matrix4f(m);
}

LLViewerCamera::LLViewerCamera() : LLCamera()
{
    calcProjection(getFar());
    mCameraFOVDefault = DEFAULT_FIELD_OF_VIEW;
    mPrevCameraFOVDefault = DEFAULT_FIELD_OF_VIEW;
    mCosHalfCameraFOV = cosf(mCameraFOVDefault * 0.5f);
    mPixelMeterRatio = 0.f;
    mScreenPixelArea = 0;
    mZoomFactor = 1.f;
    mZoomSubregion = 1;
    mAverageSpeed = 0.f;
    mAverageAngularSpeed = 0.f;

    mCameraAngleChangedSignal = gSavedSettings.getControl("CameraAngle")->getCommitSignal()->connect(boost::bind(&LLViewerCamera::updateCameraAngle, this, _2));
}

LLViewerCamera::~LLViewerCamera()
{
    mCameraAngleChangedSignal.disconnect();
}

void LLViewerCamera::updateCameraLocation(const LLVector3 &center, const LLVector3 &up_direction, const LLVector3 &point_of_interest)
{
    // do not update if avatar didn't move
    if (!LLViewerJoystick::getInstance()->getCameraNeedsUpdate())
    {
        return;
    }

    LLVector3 last_position;
    LLVector3 last_axis;
    last_position = getOrigin();
    last_axis     = getAtAxis();

    mLastPointOfInterest = point_of_interest;

    LLViewerRegion* regp = LLWorld::instance().getRegionFromPosAgent(getOrigin());
    if (!regp)
    {
        regp = gAgent.getRegion();
    }

    F32 water_height = (NULL != regp) ? regp->getWaterHeight() : 0.f;

    LLVector3 origin = center;

    {
        if (origin.mV[2] > water_height)
        {
            origin.mV[2] = llmax(origin.mV[2], water_height + 0.20f);
        }
        else
        {
            origin.mV[2] = llmin(origin.mV[2], water_height - 0.20f);
        }
    }

    setOriginAndLookAt(origin, up_direction, point_of_interest);

    mVelocityDir = origin - last_position ;
    F32 dpos = mVelocityDir.normVec() ;
    LLQuaternion rotation;
    rotation.shortestArc(last_axis, getAtAxis());

    F32 x, y, z;
    F32 drot;
    rotation.getAngleAxis(&drot, &x, &y, &z);

    add(sVelocityStat, dpos);
    add(sAngularVelocityStat, drot);

    mAverageSpeed = LLTrace::get_frame_recording().getPeriodMeanPerSec(sVelocityStat, 50);
    mAverageAngularSpeed = LLTrace::get_frame_recording().getPeriodMeanPerSec(sAngularVelocityStat);
    mCosHalfCameraFOV = cosf(0.5f * getView() * llmax(1.0f, getAspect()));

    // update pixel meter ratio using default fov, not modified one
    mPixelMeterRatio = getViewHeightInPixels()/ (2.f*tanf(mCameraFOVDefault*0.5));
    // update screen pixel area
    mScreenPixelArea =(S32)((F32)getViewHeightInPixels() * ((F32)getViewHeightInPixels() * getAspect()));
}

const LLMatrix4 &LLViewerCamera::getProjection() const
{
    calcProjection(getFar());
    return mProjectionMatrix;

}

const LLMatrix4 &LLViewerCamera::getModelview() const
{
    LLMatrix4 cfr(OGL_TO_CFR_ROTATION);
    getMatrixToLocal(mModelviewMatrix);
    mModelviewMatrix *= cfr;
    return mModelviewMatrix;
}

void LLViewerCamera::calcProjection(const F32 far_distance) const
{
    F32 fov_y, z_far, z_near, aspect, f;
    fov_y = getView();
    z_far = far_distance;
    z_near = getNear();
    aspect = getAspect();

    f = 1/tan(fov_y*0.5f);

    mProjectionMatrix.setZero();
    mProjectionMatrix.mMatrix[0][0] = f/aspect;
    mProjectionMatrix.mMatrix[1][1] = f;
    mProjectionMatrix.mMatrix[2][2] = (z_far + z_near)/(z_near - z_far);
    mProjectionMatrix.mMatrix[3][2] = (2*z_far*z_near)/(z_near - z_far);
    mProjectionMatrix.mMatrix[2][3] = -1;
}

// Sets up opengl state for 3D drawing.  If for selection, also
// sets up a pick matrix.  x and y are ignored if for_selection is false.
// The picking region is centered on x,y and has the specified width and
// height.

//static
void LLViewerCamera::updateFrustumPlanes(LLCamera& camera, bool ortho, bool zflip, bool no_hacks)
{
#if GLU_VERSION_1_1
    GLint* viewport = (GLint*) gGLViewport;
    F64 model[16];
    F64 proj[16];

    for (U32 i = 0; i < 16; i++)
    {
        model[i] = (F64) gGLModelView[i];
        proj[i] = (F64) gGLProjection[i];
    }

    GLdouble objX,objY,objZ;

    LLVector3 frust[8];

    if (no_hacks)
    {
        gluUnProject(viewport[0],viewport[1],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[0].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[1].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1]+viewport[3],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[2].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0],viewport[1]+viewport[3],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[3].setVec((F32)objX,(F32)objY,(F32)objZ);

        gluUnProject(viewport[0],viewport[1],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[4].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[5].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1]+viewport[3],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[6].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0],viewport[1]+viewport[3],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[7].setVec((F32)objX,(F32)objY,(F32)objZ);
    }
    else if (zflip)
    {
        gluUnProject(viewport[0],viewport[1]+viewport[3],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[0].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1]+viewport[3],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[1].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[2].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0],viewport[1],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[3].setVec((F32)objX,(F32)objY,(F32)objZ);

        gluUnProject(viewport[0],viewport[1]+viewport[3],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[4].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1]+viewport[3],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[5].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[6].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0],viewport[1],1,model,proj,viewport,&objX,&objY,&objZ);
        frust[7].setVec((F32)objX,(F32)objY,(F32)objZ);

        for (U32 i = 0; i < 4; i++)
        {
            frust[i+4] = frust[i+4]-frust[i];
            frust[i+4].normVec();
            frust[i+4] = frust[i] + frust[i+4]*camera.getFar();
        }
    }
    else
    {
        gluUnProject(viewport[0],viewport[1],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[0].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[1].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0]+viewport[2],viewport[1]+viewport[3],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[2].setVec((F32)objX,(F32)objY,(F32)objZ);
        gluUnProject(viewport[0],viewport[1]+viewport[3],0,model,proj,viewport,&objX,&objY,&objZ);
        frust[3].setVec((F32)objX,(F32)objY,(F32)objZ);

        if (ortho)
        {
            LLVector3 far_shift = camera.getAtAxis()*camera.getFar()*2.f;
            for (U32 i = 0; i < 4; i++)
            {
                frust[i+4] = frust[i] + far_shift;
            }
        }
        else
        {
            for (U32 i = 0; i < 4; i++)
            {
                LLVector3 vec = frust[i] - camera.getOrigin();
                vec.normVec();
                frust[i+4] = camera.getOrigin() + vec*camera.getFar();
            }
        }
    }

    camera.calcAgentFrustumPlanes(frust);
#endif // GLU_VERSION_1_1
}

void LLViewerCamera::setPerspective(bool for_selection,
                                    S32 x, S32 y_from_bot, S32 width, S32 height,
                                    bool limit_select_distance,
                                    F32 z_near, F32 z_far)
{
    F32 fov_y, aspect;
    fov_y = RAD_TO_DEG * getView();
    bool z_default_far = false;
    if (z_far <= 0)
    {
        z_default_far = true;
        z_far = getFar();
    }
    if (z_near <= 0)
    {
        z_near = getNear();
    }
    aspect = getAspect();

    // Load camera view matrix
    gGL.matrixMode(LLRender::MM_PROJECTION);
    gGL.loadIdentity();

    glh::matrix4f proj_mat;

    if (for_selection)
    {
        // make a tiny little viewport
        // anything drawn into this viewport will be "selected"

        GLint viewport[4];
        viewport[0] = gViewerWindow->getWorldViewRectRaw().mLeft;
        viewport[1] = gViewerWindow->getWorldViewRectRaw().mBottom;
        viewport[2] = gViewerWindow->getWorldViewRectRaw().getWidth();
        viewport[3] = gViewerWindow->getWorldViewRectRaw().getHeight();

        proj_mat = gl_pick_matrix(x+width/2.f, y_from_bot+height/2.f, (GLfloat) width, (GLfloat) height, viewport);

        if (limit_select_distance)
        {
            // ...select distance from control
            z_far = gSavedSettings.getF32("MaxSelectDistance");
        }
        else
        {
            z_far = gAgentCamera.mDrawDistance;
        }
    }
    else
    {
        // Only override the far clip if it's not passed in explicitly.
        if (z_default_far)
        {
            z_far = MAX_FAR_CLIP;
        }
        glViewport(x, y_from_bot, width, height);
        gGLViewport[0] = x;
        gGLViewport[1] = y_from_bot;
        gGLViewport[2] = width;
        gGLViewport[3] = height;
    }

    if (mZoomFactor > 1.f)
    {
        float offset = mZoomFactor - 1.f;
        int pos_y = mZoomSubregion / llceil(mZoomFactor);
        int pos_x = mZoomSubregion - (pos_y*llceil(mZoomFactor));
        glh::matrix4f translate;
        translate.set_translate(glh::vec3f(offset - (F32)pos_x * 2.f, offset - (F32)pos_y * 2.f, 0.f));
        glh::matrix4f scale;
        scale.set_scale(glh::vec3f(mZoomFactor, mZoomFactor, 1.f));

        proj_mat = scale*proj_mat;
        proj_mat = translate*proj_mat;
    }

    calcProjection(z_far); // Update the projection matrix cache

    proj_mat *= gl_perspective(fov_y,aspect,z_near,z_far);

    gGL.loadMatrix(proj_mat.m);

    for (U32 i = 0; i < 16; i++)
    {
        gGLProjection[i] = proj_mat.m[i];
    }

    gGL.matrixMode(LLRender::MM_MODELVIEW);

    glh::matrix4f modelview((GLfloat*) OGL_TO_CFR_ROTATION);

    GLfloat         ogl_matrix[16];

    getOpenGLTransform(ogl_matrix);

    modelview *= glh::matrix4f(ogl_matrix);

    gGL.loadMatrix(modelview.m);

    if (for_selection && (width > 1 || height > 1))
    {
        // NB: as of this writing, i believe the code below is broken (doesn't take into account the world view, assumes entire window)
        // however, it is also unused (the GL matricies are used for selection, (see LLCamera::sphereInFrustum())) and so i'm not
        // comfortable hacking on it.
        calculateFrustumPlanesFromWindow((F32)(x - width / 2) / (F32)gViewerWindow->getWindowWidthScaled() - 0.5f,
                                (F32)(y_from_bot - height / 2) / (F32)gViewerWindow->getWindowHeightScaled() - 0.5f,
                                (F32)(x + width / 2) / (F32)gViewerWindow->getWindowWidthScaled() - 0.5f,
                                (F32)(y_from_bot + height / 2) / (F32)gViewerWindow->getWindowHeightScaled() - 0.5f);

    }

    // if not picking and not doing a snapshot, cache various GL matrices
    if (!for_selection && mZoomFactor == 1.f)
    {
        // Save GL matrices for access elsewhere in code, especially project_world_to_screen
        for (U32 i = 0; i < 16; i++)
        {
            gGLModelView[i] = modelview.m[i];
        }
    }

    updateFrustumPlanes(*this);
}


// Uses the last GL matrices set in set_perspective to project a point from
// screen coordinates to the agent's region.
void LLViewerCamera::projectScreenToPosAgent(const S32 screen_x, const S32 screen_y, LLVector3* pos_agent) const
{
    GLdouble x, y, z;

    F64 mdlv[16];
    F64 proj[16];

    for (U32 i = 0; i < 16; i++)
    {
        mdlv[i] = (F64) gGLModelView[i];
        proj[i] = (F64) gGLProjection[i];
    }

#if GLU_VERSION_1_1
    gluUnProject(
        GLdouble(screen_x), GLdouble(screen_y), 0.0,
        mdlv, proj, (GLint*)gGLViewport,
        &x,
        &y,
        &z );
#endif
    pos_agent->setVec( (F32)x, (F32)y, (F32)z );
}

// Uses the last GL matrices set in set_perspective to project a point from
// the agent's region space to screen coordinates.  Returns true if point in within
// the current window.
bool LLViewerCamera::projectPosAgentToScreen(const LLVector3 &pos_agent, LLCoordGL &out_point, const bool clamp) const
{
    bool in_front = true;
    GLdouble    x, y, z;            // object's window coords, GL-style

    LLVector3 dir_to_point = pos_agent - getOrigin();
    dir_to_point /= dir_to_point.magVec();

    if (dir_to_point * getAtAxis() < 0.f)
    {
        if (clamp)
        {
            return false;
        }
        else
        {
            in_front = false;
        }
    }

    LLRect world_view_rect = gViewerWindow->getWorldViewRectRaw();
    S32 viewport[4];
    viewport[0] = world_view_rect.mLeft;
    viewport[1] = world_view_rect.mBottom;
    viewport[2] = world_view_rect.getWidth();
    viewport[3] = world_view_rect.getHeight();

    F64 mdlv[16];
    F64 proj[16];

    for (U32 i = 0; i < 16; i++)
    {
        mdlv[i] = (F64) gGLModelView[i];
        proj[i] = (F64) gGLProjection[i];
    }

#if GLU_VERSION_1_1
    if (GL_TRUE == gluProject(pos_agent.mV[VX], pos_agent.mV[VY], pos_agent.mV[VZ],
                                mdlv, proj, (GLint*)viewport,
                                &x, &y, &z))
    {
        // convert screen coordinates to virtual UI coordinates
        x /= gViewerWindow->getDisplayScale().mV[VX];
        y /= gViewerWindow->getDisplayScale().mV[VY];

        // should now have the x,y coords of grab_point in screen space
        LLRect world_rect = gViewerWindow->getWorldViewRectScaled();

        // convert to pixel coordinates
        S32 int_x = lltrunc(x);
        S32 int_y = lltrunc(y);

        bool valid = true;

        if (clamp)
        {
            if (int_x < world_rect.mLeft)
            {
                out_point.mX = world_rect.mLeft;
                valid = false;
            }
            else if (int_x > world_rect.mRight)
            {
                out_point.mX = world_rect.mRight;
                valid = false;
            }
            else
            {
                out_point.mX = int_x;
            }

            if (int_y < world_rect.mBottom)
            {
                out_point.mY = world_rect.mBottom;
                valid = false;
            }
            else if (int_y > world_rect.mTop)
            {
                out_point.mY = world_rect.mTop;
                valid = false;
            }
            else
            {
                out_point.mY = int_y;
            }
            return valid;
        }
        else
        {
            out_point.mX = int_x;
            out_point.mY = int_y;

            if (int_x < world_rect.mLeft)
            {
                valid = false;
            }
            else if (int_x > world_rect.mRight)
            {
                valid = false;
            }
            if (int_y < world_rect.mBottom)
            {
                valid = false;
            }
            else if (int_y > world_rect.mTop)
            {
                valid = false;
            }

            return in_front && valid;
        }
    }
    else
#endif // GLU_VERSION_1_1
    {
        return false;
    }
}

// Uses the last GL matrices set in set_perspective to project a point from
// the agent's region space to the nearest edge in screen coordinates.
// Returns true if projection succeeds.
bool LLViewerCamera::projectPosAgentToScreenEdge(const LLVector3 &pos_agent,
                                                LLCoordGL &out_point) const
{
#if GLU_VERSION_1_1
    LLVector3 dir_to_point = pos_agent - getOrigin();
    dir_to_point /= dir_to_point.magVec();

    bool in_front = true;
    if (dir_to_point * getAtAxis() < 0.f)
    {
        in_front = false;
    }

    LLRect world_view_rect = gViewerWindow->getWorldViewRectRaw();
    S32 viewport[4];
    viewport[0] = world_view_rect.mLeft;
    viewport[1] = world_view_rect.mBottom;
    viewport[2] = world_view_rect.getWidth();
    viewport[3] = world_view_rect.getHeight();
    GLdouble    x, y, z;            // object's window coords, GL-style

    F64 mdlv[16];
    F64 proj[16];

    for (U32 i = 0; i < 16; i++)
    {
        mdlv[i] = (F64) gGLModelView[i];
        proj[i] = (F64) gGLProjection[i];
    }

    if (GL_TRUE == gluProject(pos_agent.mV[VX], pos_agent.mV[VY],
                              pos_agent.mV[VZ], mdlv,
                              proj, (GLint*)viewport,
                              &x, &y, &z))
    {
        x /= gViewerWindow->getDisplayScale().mV[VX];
        y /= gViewerWindow->getDisplayScale().mV[VY];
        // should now have the x,y coords of grab_point in screen space
        const LLRect& world_rect = gViewerWindow->getWorldViewRectScaled();

        // ...sanity check
        S32 int_x = lltrunc(x);
        S32 int_y = lltrunc(y);

        // find the center
        GLdouble center_x = (GLdouble)world_rect.getCenterX();
        GLdouble center_y = (GLdouble)world_rect.getCenterY();

        if (x == center_x  &&  y == center_y)
        {
            // can't project to edge from exact center
            return false;
        }

        // find the line from center to local
        GLdouble line_x = x - center_x;
        GLdouble line_y = y - center_y;

        int_x = lltrunc(center_x);
        int_y = lltrunc(center_y);


        if (0.f == line_x)
        {
            // the slope of the line is undefined
            if (line_y > 0.f)
            {
                int_y = world_rect.mTop;
            }
            else
            {
                int_y = world_rect.mBottom;
            }
        }
        else if (0 == world_rect.getWidth())
        {
            // the diagonal slope of the view is undefined
            if (y < world_rect.mBottom)
            {
                int_y = world_rect.mBottom;
            }
            else if ( y > world_rect.mTop)
            {
                int_y = world_rect.mTop;
            }
        }
        else
        {
            F32 line_slope = (F32)(line_y / line_x);
            F32 rect_slope = ((F32)world_rect.getHeight()) / ((F32)world_rect.getWidth());

            if (fabs(line_slope) > rect_slope)
            {
                if (line_y < 0.f)
                {
                    // bottom
                    int_y = world_rect.mBottom;
                }
                else
                {
                    // top
                    int_y = world_rect.mTop;
                }
                int_x = lltrunc(((GLdouble)int_y - center_y) / line_slope + center_x);
            }
            else if (fabs(line_slope) < rect_slope)
            {
                if (line_x < 0.f)
                {
                    // left
                    int_x = world_rect.mLeft;
                }
                else
                {
                    // right
                    int_x = world_rect.mRight;
                }
                int_y = lltrunc(((GLdouble)int_x - center_x) * line_slope + center_y);
            }
            else
            {
                // exactly parallel ==> push to the corners
                if (line_x > 0.f)
                {
                    int_x = world_rect.mRight;
                }
                else
                {
                    int_x = world_rect.mLeft;
                }
                if (line_y > 0.0f)
                {
                    int_y = world_rect.mTop;
                }
                else
                {
                    int_y = world_rect.mBottom;
                }
            }
        }
        if (!in_front)
        {
            int_x = world_rect.mLeft + world_rect.mRight - int_x;
            int_y = world_rect.mBottom + world_rect.mTop - int_y;
        }

        out_point.mX = int_x + world_rect.mLeft;
        out_point.mY = int_y + world_rect.mBottom;
        return true;
    }
#endif // GLU_VERSION_1_1
    return false;
}


void LLViewerCamera::getPixelVectors(const LLVector3 &pos_agent, LLVector3 &up, LLVector3 &right)
{
    LLVector3 to_vec = pos_agent - getOrigin();

    F32 at_dist = to_vec * getAtAxis();

    F32 height_meters = at_dist* (F32)tan(getView()/2.f);
    F32 height_pixels = getViewHeightInPixels()/2.f;

    F32 pixel_aspect = gViewerWindow->getWindow()->getPixelAspectRatio();

    F32 meters_per_pixel = height_meters / height_pixels;
    up = getUpAxis() * meters_per_pixel * gViewerWindow->getDisplayScale().mV[VY];
    right = -1.f * pixel_aspect * meters_per_pixel * getLeftAxis() * gViewerWindow->getDisplayScale().mV[VX];
}

LLVector3 LLViewerCamera::roundToPixel(const LLVector3 &pos_agent)
{
    F32 dist = (pos_agent - getOrigin()).magVec();
    // Convert to screen space and back, preserving the depth.
    LLCoordGL screen_point;
    if (!projectPosAgentToScreen(pos_agent, screen_point, false))
    {
        // Off the screen, just return the original position.
        return pos_agent;
    }

    LLVector3 ray_dir;

    projectScreenToPosAgent(screen_point.mX, screen_point.mY, &ray_dir);
    ray_dir -= getOrigin();
    ray_dir.normVec();

    LLVector3 pos_agent_rounded = getOrigin() + ray_dir*dist;

    /*
    LLVector3 pixel_x, pixel_y;
    getPixelVectors(pos_agent_rounded, pixel_y, pixel_x);
    pos_agent_rounded += 0.5f*pixel_x, 0.5f*pixel_y;
    */
    return pos_agent_rounded;
}

bool LLViewerCamera::cameraUnderWater() const
{
    LLViewerRegion* regionp = LLWorld::instance().getRegionFromPosAgent(getOrigin());

    if (gPipeline.mHeroProbeManager.isMirrorPass())
    {
        // TODO: figure out how to handle this case
        return false;
    }

    if (!regionp)
    {
        regionp = gAgent.getRegion();
    }

    if(!regionp)
    {
        return false ;
    }

    return getOrigin().mV[VZ] < regionp->getWaterHeight();
}

bool LLViewerCamera::areVertsVisible(LLViewerObject* volumep, bool all_verts)
{
    S32 i, num_faces;
    LLDrawable* drawablep = volumep->mDrawable;

    if (!drawablep)
    {
        return false;
    }

    LLVolume* volume = volumep->getVolume();
    if (!volume)
    {
        return false;
    }

    LLVOVolume* vo_volume = (LLVOVolume*) volumep;

    vo_volume->updateRelativeXform();
    LLMatrix4 mat = vo_volume->getRelativeXform();

    LLMatrix4 render_mat(vo_volume->getRenderRotation(), LLVector4(vo_volume->getRenderPosition()));

    LLMatrix4a render_mata;
    render_mata.loadu(render_mat);
    LLMatrix4a mata;
    mata.loadu(mat);

    num_faces = volume->getNumVolumeFaces();
    for (i = 0; i < num_faces; i++)
    {
        const LLVolumeFace& face = volume->getVolumeFace(i);

        for (S32 v = 0; v < face.mNumVertices; v++)
        {
            const LLVector4a& src_vec = face.mPositions[v];
            LLVector4a vec;
            mata.affineTransform(src_vec, vec);

            if (drawablep->isActive())
            {
                LLVector4a t = vec;
                render_mata.affineTransform(t, vec);
            }

            bool in_frustum = pointInFrustum(LLVector3(vec.getF32ptr())) > 0;

            if (( !in_frustum && all_verts) ||
                 (in_frustum && !all_verts))
            {
                return !all_verts;
            }
        }
    }
    return all_verts;
}

extern bool gCubeSnapshot;

// changes local camera and broadcasts change
/* virtual */ void LLViewerCamera::setView(F32 vertical_fov_rads)
{
    llassert(!gCubeSnapshot);

    F32 old_fov = LLViewerCamera::getInstance()->getView();

    // cap the FoV
    vertical_fov_rads = llclamp(vertical_fov_rads, getMinView(), getMaxView());

    if (vertical_fov_rads == old_fov) return;

    // send the new value to the simulator
    LLMessageSystem* msg = gMessageSystem;
    msg->newMessageFast(_PREHASH_AgentFOV);
    msg->nextBlockFast(_PREHASH_AgentData);
    msg->addUUIDFast(_PREHASH_AgentID, gAgent.getID());
    msg->addUUIDFast(_PREHASH_SessionID, gAgent.getSessionID());
    msg->addU32Fast(_PREHASH_CircuitCode, gMessageSystem->mOurCircuitCode);

    msg->nextBlockFast(_PREHASH_FOVBlock);
    msg->addU32Fast(_PREHASH_GenCounter, 0);
    msg->addF32Fast(_PREHASH_VerticalAngle, vertical_fov_rads);

    gAgent.sendReliableMessage();

    // sync the camera with the new value
    LLCamera::setView(vertical_fov_rads); // call base implementation
}

void LLViewerCamera::setViewNoBroadcast(F32 vertical_fov_rads)
{
    LLCamera::setView(vertical_fov_rads);
}

void LLViewerCamera::setDefaultFOV(F32 vertical_fov_rads)
{
    vertical_fov_rads = llclamp(vertical_fov_rads, getMinView(), getMaxView());
    setView(vertical_fov_rads);
    mCameraFOVDefault = vertical_fov_rads;
    mCosHalfCameraFOV = cosf(mCameraFOVDefault * 0.5f);
}

bool LLViewerCamera::isDefaultFOVChanged()
{
    if(mPrevCameraFOVDefault != mCameraFOVDefault)
    {
        mPrevCameraFOVDefault = mCameraFOVDefault;
        return !gSavedSettings.getBOOL("IgnoreFOVZoomForLODs");
    }
    return false;
}

void LLViewerCamera::updateCameraAngle(const LLSD& value)
{
    setDefaultFOV(value.asReal());
}