llcamera.cpp

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#include "linden_common.h"

#include "llmath.h"
#include "llcamera.h"

// ---------------- Constructors and destructors ----------------

LLCamera::LLCamera() :
        LLCoordFrame(),
        mView(DEFAULT_FIELD_OF_VIEW),
        mAspect(DEFAULT_ASPECT_RATIO),
        mViewHeightInPixels( -1 ),                      // invalid height
        mNearPlane(DEFAULT_NEAR_PLANE),
        mFarPlane(DEFAULT_FAR_PLANE),
        mFixedDistance(-1.f)
{
        calculateFrustumPlanes();
} 


LLCamera::LLCamera(F32 z_field_of_view, F32 aspect_ratio, S32 view_height_in_pixels, F32 near_plane, F32 far_plane) :
        LLCoordFrame(),
        mView(z_field_of_view),
        mAspect(aspect_ratio),
        mViewHeightInPixels(view_height_in_pixels),
        mNearPlane(near_plane),
        mFarPlane(far_plane),
        mFixedDistance(-1.f)
{
        if (mView < MIN_FIELD_OF_VIEW)                  { mView = MIN_FIELD_OF_VIEW; }
        else if (mView > MAX_FIELD_OF_VIEW)             { mView = MAX_FIELD_OF_VIEW; }

        if (mAspect < MIN_ASPECT_RATIO)                 { mAspect = MIN_ASPECT_RATIO; }
        else if (mAspect > MAX_ASPECT_RATIO)    { mAspect = MAX_ASPECT_RATIO; }

        if (mNearPlane < MIN_NEAR_PLANE)                { mNearPlane = MIN_NEAR_PLANE; }
        else if (mNearPlane > MAX_NEAR_PLANE)   { mNearPlane = MAX_NEAR_PLANE; }

        if (mFarPlane < 0)                                              { mFarPlane = DEFAULT_FAR_PLANE; }
        else if (mFarPlane < MIN_FAR_PLANE)             { mFarPlane = MIN_FAR_PLANE; }
        else if (mFarPlane > MAX_FAR_PLANE)             { mFarPlane = MAX_FAR_PLANE; }

        calculateFrustumPlanes();
} 



// ---------------- LLCamera::setFoo() member functions ----------------

void LLCamera::setView(F32 field_of_view) 
{
        mView = field_of_view;
        if (mView < MIN_FIELD_OF_VIEW)                  { mView = MIN_FIELD_OF_VIEW; }
        else if (mView > MAX_FIELD_OF_VIEW)             { mView = MAX_FIELD_OF_VIEW; }
        calculateFrustumPlanes();
}

void LLCamera::setViewHeightInPixels(S32 height)
{
        mViewHeightInPixels = height;

        // Don't really need to do this, but update the pixel meter ratio with it.
        calculateFrustumPlanes();
}

void LLCamera::setAspect(F32 aspect_ratio) 
{
        mAspect = aspect_ratio;
        if (mAspect < MIN_ASPECT_RATIO)                 { mAspect = MIN_ASPECT_RATIO; }
        else if (mAspect > MAX_ASPECT_RATIO)    { mAspect = MAX_ASPECT_RATIO; }
        calculateFrustumPlanes();
}


void LLCamera::setNear(F32 near_plane) 
{
        mNearPlane = near_plane;
        if (mNearPlane < MIN_NEAR_PLANE)                { mNearPlane = MIN_NEAR_PLANE; }
        else if (mNearPlane > MAX_NEAR_PLANE)   { mNearPlane = MAX_NEAR_PLANE; }
        calculateFrustumPlanes();
}


void LLCamera::setFar(F32 far_plane) 
{
        mFarPlane = far_plane;
        if (mFarPlane < MIN_FAR_PLANE)                  { mFarPlane = MIN_FAR_PLANE; }
        else if (mFarPlane > MAX_FAR_PLANE)             { mFarPlane = MAX_FAR_PLANE; }
        calculateFrustumPlanes();
}


// ---------------- read/write to buffer ---------------- 

size_t LLCamera::writeFrustumToBuffer(char *buffer) const
{
        memcpy(buffer, &mView, sizeof(F32));            /* Flawfinder: ignore */                
        buffer += sizeof(F32);
        memcpy(buffer, &mAspect, sizeof(F32));          /* Flawfinder: ignore */
        buffer += sizeof(F32);
        memcpy(buffer, &mNearPlane, sizeof(F32));       /* Flawfinder: ignore */
        buffer += sizeof(F32);
        memcpy(buffer, &mFarPlane, sizeof(F32));                /* Flawfinder: ignore */
        return 4*sizeof(F32);
}

size_t LLCamera::readFrustumFromBuffer(const char *buffer)
{
        memcpy(&mView, buffer, sizeof(F32));            /* Flawfinder: ignore */
        buffer += sizeof(F32);
        memcpy(&mAspect, buffer, sizeof(F32));          /* Flawfinder: ignore */
        buffer += sizeof(F32);
        memcpy(&mNearPlane, buffer, sizeof(F32));       /* Flawfinder: ignore */
        buffer += sizeof(F32);
        memcpy(&mFarPlane, buffer, sizeof(F32));                /* Flawfinder: ignore */
        return 4*sizeof(F32);
}


// ---------------- test methods  ---------------- 

int LLCamera::AABBInFrustum(const LLVector3 &center, const LLVector3& radius) 
{
        static const LLVector3 scaler[] = {
                LLVector3(-1,-1,-1),
                LLVector3( 1,-1,-1),
                LLVector3(-1, 1,-1),
                LLVector3( 1, 1,-1),
                LLVector3(-1,-1, 1),
                LLVector3( 1,-1, 1),
                LLVector3(-1, 1, 1),
                LLVector3( 1, 1, 1)
        };

        U8 mask = 0;
        S32 result = 2;

        for (int i = 0; i < 6; i++)
        {
                mask = mAgentPlaneMask[i];
                LLPlane p = mAgentPlanes[i];
                LLVector3 n = LLVector3(p);
                float d = p.mV[3];
                LLVector3 rscale = radius.scaledVec(scaler[mask]);

                LLVector3 minp = center - rscale;
                LLVector3 maxp = center + rscale;

                if (n * minp > -d) 
                {
                        return 0;
                }
        
                if (n * maxp > -d)
                {
                        result = 1;
                }
        }

        return result;
}

int LLCamera::sphereInFrustumQuick(const LLVector3 &sphere_center, const F32 radius) 
{
        LLVector3 dist = sphere_center-mFrustCenter;
        float dsq = dist * dist;
        float rsq = mFarPlane*0.5f + radius;
        rsq *= rsq;

        if (dsq < rsq) 
        {
                return 1;
        }
        
        return 0;       
}

// HACK: This version is still around because the version below doesn't work
// unless the agent planes are initialized.
// Return 1 if sphere is in frustum, 2 if fully in frustum, otherwise 0.
// NOTE: 'center' is in absolute frame.
int LLCamera::sphereInFrustumOld(const LLVector3 &sphere_center, const F32 radius) const 
{
        // Returns 1 if sphere is in frustum, 0 if not.
        // modified so that default view frust is along X with Z vertical
        F32 x, y, z, rightDist, leftDist, topDist, bottomDist;

        // Subtract the view position 
        //LLVector3 relative_center;
        //relative_center = sphere_center - getOrigin();
        LLVector3 rel_center(sphere_center);
        rel_center -= mOrigin;

        bool all_in = TRUE;

        // Transform relative_center.x to camera frame
        x = mXAxis * rel_center;
        if (x < MIN_NEAR_PLANE - radius)
        {
                return 0;
        }
        else if (x < MIN_NEAR_PLANE + radius)
        {
                all_in = FALSE;
        }

        if (x > mFarPlane + radius)
        {
                return 0;
        }
        else if (x > mFarPlane - radius)
        {
                all_in = FALSE;
        }

        // Transform relative_center.y to camera frame
        y = mYAxis * rel_center;

        // distance to plane is the dot product of (x, y, 0) * plane_normal
        rightDist = x * mLocalPlanes[PLANE_RIGHT][VX] + y * mLocalPlanes[PLANE_RIGHT][VY];
        if (rightDist < -radius)
        {
                return 0;
        }
        else if (rightDist < radius)
        {
                all_in = FALSE;
        }

        leftDist = x * mLocalPlanes[PLANE_LEFT][VX] + y * mLocalPlanes[PLANE_LEFT][VY];
        if (leftDist < -radius)
        {
                return 0;
        }
        else if (leftDist < radius)
        {
                all_in = FALSE;
        }

        // Transform relative_center.y to camera frame
        z = mZAxis * rel_center;

        topDist = x * mLocalPlanes[PLANE_TOP][VX] + z * mLocalPlanes[PLANE_TOP][VZ];
        if (topDist < -radius)
        {
                return 0;
        }
        else if (topDist < radius)
        {
                all_in = FALSE;
        }

        bottomDist = x * mLocalPlanes[PLANE_BOTTOM][VX] + z * mLocalPlanes[PLANE_BOTTOM][VZ];
        if (bottomDist < -radius)
        {
                return 0;
        }
        else if (bottomDist < radius)
        {
                all_in = FALSE;
        }

        if (all_in)
        {
                return 2;
        }

        return 1;
}


// HACK: This (presumably faster) version only currently works if you set up the
// frustum planes using GL.  At some point we should get those planes through another
// mechanism, and then we can get rid of the "old" version above.

// Return 1 if sphere is in frustum, 2 if fully in frustum, otherwise 0.
// NOTE: 'center' is in absolute frame.
int LLCamera::sphereInFrustum(const LLVector3 &sphere_center, const F32 radius) const 
{
        // Returns 1 if sphere is in frustum, 0 if not.
        int res = 2;
        for (int i = 0; i < 6; i++)
        {
                float d = mAgentPlanes[i].dist(sphere_center);

                if (d > radius) 
                {
                        return 0;
                }

                if (d > -radius)
                {
                        res = 1;
                }
        }

        return res;
}


// return height of a sphere of given radius, located at center, in pixels
F32 LLCamera::heightInPixels(const LLVector3 &center, F32 radius ) const
{
        if (radius == 0.f) return 0.f;

        // If height initialized
        if (mViewHeightInPixels > -1)
        {
                // Convert sphere to coord system with 0,0,0 at camera
                LLVector3 vec = center - mOrigin;

                // Compute distance to sphere
                F32 dist = vec.magVec();

                // Calculate angle of whole object
                F32 angle = 2.0f * (F32) atan2(radius, dist);

                // Calculate fraction of field of view
                F32 fraction_of_fov = angle / mView;

                // Compute number of pixels tall, based on vertical field of view
                return (fraction_of_fov * mViewHeightInPixels);
        }
        else
        {
                // return invalid height
                return -1.0f;
        }
}

// If pos is visible, return the distance from pos to the camera.
// Use fudge distance to scale rad against top/bot/left/right planes
// Otherwise, return -distance
F32 LLCamera::visibleDistance(const LLVector3 &pos, F32 rad, F32 fudgedist, U32 planemask) const
{
        if (mFixedDistance > 0)
        {
                return mFixedDistance;
        }
        LLVector3 dvec = pos - mOrigin;
        // Check visibility
        F32 dist = dvec.magVec();
        if (dist > rad)
        {
                F32 dp,tdist;
                dp = dvec * mXAxis;
                if (dp < -rad)
                        return -dist;

                rad *= fudgedist;
                LLVector3 tvec(pos);
                for (int p=0; p<PLANE_NUM; p++)
                {
                        if (!(planemask & (1<<p)))
                                continue;
                        tdist = -(mWorldPlanes[p].dist(tvec));
                        if (tdist > rad)
                                return -dist;
                }
        }
        return dist;
}

// Like visibleDistance, except uses mHorizPlanes[], which are left and right
//  planes perpindicular to (0,0,1) in world space
F32 LLCamera::visibleHorizDistance(const LLVector3 &pos, F32 rad, F32 fudgedist, U32 planemask) const
{
        if (mFixedDistance > 0)
        {
                return mFixedDistance;
        }
        LLVector3 dvec = pos - mOrigin;
        // Check visibility
        F32 dist = dvec.magVec();
        if (dist > rad)
        {
                rad *= fudgedist;
                LLVector3 tvec(pos);
                for (int p=0; p<HORIZ_PLANE_NUM; p++)
                {
                        if (!(planemask & (1<<p)))
                                continue;
                        F32 tdist = -(mHorizPlanes[p].dist(tvec));
                        if (tdist > rad)
                                return -dist;
                }
        }
        return dist;
}

// ---------------- friends and operators ----------------  

std::ostream& operator<<(std::ostream &s, const LLCamera &C) 
{
        s << "{ \n";
        s << "  Center = " << C.getOrigin() << "\n";
        s << "  AtAxis = " << C.getXAxis() << "\n";
        s << "  LeftAxis = " << C.getYAxis() << "\n";
        s << "  UpAxis = " << C.getZAxis() << "\n";
        s << "  View = " << C.getView() << "\n";
        s << "  Aspect = " << C.getAspect() << "\n";
        s << "  NearPlane   = " << C.mNearPlane << "\n";
        s << "  FarPlane    = " << C.mFarPlane << "\n";
        s << "  TopPlane    = " << C.mLocalPlanes[LLCamera::PLANE_TOP][VX] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_TOP][VY] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_TOP][VZ] << "\n";
        s << "  BottomPlane = " << C.mLocalPlanes[LLCamera::PLANE_BOTTOM][VX] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_BOTTOM][VY] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_BOTTOM][VZ] << "\n";
        s << "  LeftPlane   = " << C.mLocalPlanes[LLCamera::PLANE_LEFT][VX] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_LEFT][VY] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_LEFT][VZ] << "\n";
        s << "  RightPlane  = " << C.mLocalPlanes[LLCamera::PLANE_RIGHT][VX] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_RIGHT][VY] << "  " 
                                                        << C.mLocalPlanes[LLCamera::PLANE_RIGHT][VZ] << "\n";
        s << "}";
        return s;
}



// ----------------  private member functions ----------------

void LLCamera::calculateFrustumPlanes() 
{
        // The planes only change when any of the frustum descriptions change.
        // They are not affected by changes of the position of the Frustum
        // because they are known in the view frame and the position merely
        // provides information on how to get from the absolute frame to the 
        // view frame.

        F32 left,right,top,bottom;
        top = mFarPlane * (F32)tanf(0.5f * mView);
        bottom = -top;
        left = top * mAspect;
        right = -left;

        calculateFrustumPlanes(left, right, top, bottom);
}

LLPlane planeFromPoints(LLVector3 p1, LLVector3 p2, LLVector3 p3)
{
        LLVector3 n = ((p2-p1)%(p3-p1));
        n.normVec();

        return LLPlane(p1, n);
}


void LLCamera::calcAgentFrustumPlanes(LLVector3* frust)
{

        for (int i = 0; i < 8; i++)
        {
                mAgentFrustum[i] = frust[i];
        }

        //frust contains the 8 points of the frustum, calculate 6 planes

        //order of planes is important, keep most likely to fail in the front of the list

        //near - frust[0], frust[1], frust[2]
        mAgentPlanes[2] = planeFromPoints(frust[0], frust[1], frust[2]);

        //far  
        mAgentPlanes[5] = planeFromPoints(frust[5], frust[4], frust[6]);

        //left  
        mAgentPlanes[0] = planeFromPoints(frust[4], frust[0], frust[7]);

        //right  
        mAgentPlanes[1] = planeFromPoints(frust[1], frust[5], frust[6]);

        //top  
        mAgentPlanes[4] = planeFromPoints(frust[3], frust[2], frust[6]);

        //bottom  
        mAgentPlanes[3] = planeFromPoints(frust[1], frust[0], frust[4]);

        //cache plane octant facing mask for use in AABBInFrustum
        for (int i = 0; i < 6; i++)
        {
                U8 mask = 0;
                LLPlane p = mAgentPlanes[i];
                LLVector3 n = LLVector3(p);

                if (n.mV[0] >= 0)
                {
                        mask |= 1;
                }
                if (n.mV[1] >= 0)
                {
                        mask |= 2;
                }
                if (n.mV[2] >= 0)
                {
                        mask |= 4;
                }
                mAgentPlaneMask[i] = mask;
        }
}

void LLCamera::calculateFrustumPlanes(F32 left, F32 right, F32 top, F32 bottom)
{
        LLVector3 a, b, c;

        // For each plane we need to define 3 points (LLVector3's) in camera view space.  
        // The order in which we pass the points to planeFromPoints() matters, because the 
        // plane normal has a degeneracy of 2; we want it pointing _into_ the frustum. 

        a.setVec(0.0f, 0.0f, 0.0f);
        b.setVec(mFarPlane, right, top);
        c.setVec(mFarPlane, right, bottom);
        mLocalPlanes[PLANE_RIGHT].setVec(a, b, c);

        c.setVec(mFarPlane, left, top);
        mLocalPlanes[PLANE_TOP].setVec(a, c, b);

        b.setVec(mFarPlane, left, bottom);
        mLocalPlanes[PLANE_LEFT].setVec(a, b, c);

        c.setVec(mFarPlane, right, bottom);
        mLocalPlanes[PLANE_BOTTOM].setVec( a, c, b); 

        //calculate center and radius squared of frustum in world absolute coordinates
        mFrustCenter = X_AXIS*mFarPlane*0.5f;
        mFrustCenter = transformToAbsolute(mFrustCenter);
        mFrustRadiusSquared = mFarPlane*0.5f;
        mFrustRadiusSquared *= mFrustRadiusSquared * 1.05f; //pad radius squared by 5%
}

// x and y are in WINDOW space, so x = Y-Axis (left/right), y= Z-Axis(Up/Down)
void LLCamera::calculateFrustumPlanesFromWindow(F32 x1, F32 y1, F32 x2, F32 y2)
{
        F32 bottom, top, left, right;
        F32 view_height = (F32)tanf(0.5f * mView) * mFarPlane;
        F32 view_width = view_height * mAspect;
        
        left =   x1 * -2.f * view_width;
        right =  x2 * -2.f * view_width;
        bottom = y1 * 2.f * view_height; 
        top =    y2 * 2.f * view_height;

        calculateFrustumPlanes(left, right, top, bottom);
}

void LLCamera::calculateWorldFrustumPlanes() 
{
        F32 d;
        LLVector3 center = mOrigin - mXAxis*mNearPlane;
        mWorldPlanePos = center;
        for (int p=0; p<4; p++)
        {
                LLVector3 pnorm = LLVector3(mLocalPlanes[p]);
                LLVector3 norm = rotateToAbsolute(pnorm);
                norm.normVec();
                d = -(center * norm);
                mWorldPlanes[p] = LLPlane(norm, d);
        }
        // horizontal planes, perpindicular to (0,0,1);
        LLVector3 zaxis(0, 0, 1.0f);
        F32 yaw = getYaw();
        {
                LLVector3 tnorm = LLVector3(mLocalPlanes[PLANE_LEFT]);
                tnorm.rotVec(yaw, zaxis);
                d = -(mOrigin * tnorm);
                mHorizPlanes[HORIZ_PLANE_LEFT] = LLPlane(tnorm, d);
        }
        {
                LLVector3 tnorm = LLVector3(mLocalPlanes[PLANE_RIGHT]);
                tnorm.rotVec(yaw, zaxis);
                d = -(mOrigin * tnorm);
                mHorizPlanes[HORIZ_PLANE_RIGHT] = LLPlane(tnorm, d);
        }
}

// NOTE: this is the OpenGL matrix that will transform the default OpenGL view 
// (-Z=at, Y=up) to the default view of the LLCamera class (X=at, Z=up):
// 
// F32 cfr_transform =  {  0.f,  0.f, -1.f,  0.f,   // -Z becomes X
//                                                -1.f,  0.f,  0.f,  0.f,   // -X becomes Y
//                                         0.f,  1.f,  0.f,  0.f,   //  Y becomes Z
//                                                 0.f,  0.f,  0.f,  1.f };

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