llsurfacepatch.cpp

Go to the documentation of this file.

#include "llviewerprecompiledheaders.h"

#include "llsurfacepatch.h"
#include "llpatchvertexarray.h"
#include "llviewerobjectlist.h"
#include "llvosurfacepatch.h"
#include "llsurface.h"
#include "pipeline.h"
#include "llagent.h"
#include "timing.h"
#include "llsky.h"
#include "llviewercamera.h"

// For getting composition values
#include "llviewerregion.h"
#include "llvlcomposition.h"
#include "lldrawpool.h"
#include "noise.h"

extern U64 gFrameTime;
extern LLPipeline gPipeline;

LLSurfacePatch::LLSurfacePatch() :
                                                mDataZ(NULL),
                                                mVObjp(NULL),
                                                mLastUpdateTime(0),
                                                mSurfacep(NULL)
{
        // This flag is used to communicate between adjacent surfaces and is set
        // to non-zero values by higher classes.  
        mConnectedEdge = NO_EDGE;
        mCenterRegion = LLVector3(0.f, 0.f, 0.f);
        mOriginRegion = LLVector3(0.f, 0.f, 0.f);
        mHasReceivedData = FALSE;
        mMinZ = 0.0f;
        mMaxZ = 0.0f;
        mMeanZ = 0.0f;
        mMinComposition = 0.f;
        mMeanComposition = 0.f;
        mMaxComposition = 0.f;
        mRadius = 0.f;
        mDirty = FALSE;
        mDirtyZStats = TRUE;
        mHeightsGenerated = FALSE;
        
        S32 i;
        for (i = 0; i < 8; i++)
        {
                setNeighborPatch(i, NULL);
        }
        for (i = 0; i < 9; i++)
        {
                mNormalsInvalid[i] = TRUE;
        }
}


LLSurfacePatch::~LLSurfacePatch()
{
        mVObjp = NULL;
}


void LLSurfacePatch::dirty()
{
        // These are outside of the loop in case we're still waiting for a dirty from the
        // texture being updated...
        if (mVObjp)
        {
                mVObjp->dirtyGeom();
        }
        else
        {
                llwarns << "No viewer object for this surface patch!" << llendl;
        }

        mDirtyZStats = TRUE;
        mHeightsGenerated = FALSE;
        
        if (!mDirty)
        {
                mDirty = TRUE;
                mSurfacep->dirtySurfacePatch(this);
        }
}


void LLSurfacePatch::setSurface(LLSurface *surfacep)
{
        mSurfacep = surfacep;
        if (mVObjp == (LLVOSurfacePatch *)NULL)
        {
                llassert(mSurfacep->mType == 'l');

                mVObjp = (LLVOSurfacePatch *)gObjectList.createObjectViewer(LLViewerObject::LL_VO_SURFACE_PATCH, mSurfacep->getRegion());
                mVObjp->setPatch(this);
                mVObjp->setPositionRegion(mCenterRegion);
                gPipeline.addObject(mVObjp);
        }
} 

void LLSurfacePatch::disconnectNeighbor(LLSurface *surfacep)
{
        U32 i;
        for (i = 0; i < 8; i++)
        {
                if (getNeighborPatch(i))
                {
                        if (getNeighborPatch(i)->mSurfacep == surfacep)
                        {
                                setNeighborPatch(i, NULL);
                                mNormalsInvalid[i] = TRUE;
                        }
                }
        }

        // Clean up connected edges
        if (getNeighborPatch(EAST))
        {
                if (getNeighborPatch(EAST)->mSurfacep == surfacep)
                {
                        mConnectedEdge &= ~EAST_EDGE;
                }
        }
        if (getNeighborPatch(NORTH))
        {
                if (getNeighborPatch(NORTH)->mSurfacep == surfacep)
                {
                        mConnectedEdge &= ~NORTH_EDGE;
                }
        }
        if (getNeighborPatch(WEST))
        {
                if (getNeighborPatch(WEST)->mSurfacep == surfacep)
                {
                        mConnectedEdge &= ~WEST_EDGE;
                }
        }
        if (getNeighborPatch(SOUTH))
        {
                if (getNeighborPatch(SOUTH)->mSurfacep == surfacep)
                {
                        mConnectedEdge &= ~SOUTH_EDGE;
                }
        }
}

LLVector3 LLSurfacePatch::getPointAgent(const U32 x, const U32 y) const
{
        U32 surface_stride = mSurfacep->getGridsPerEdge();
        U32 point_offset = x + y*surface_stride;
        LLVector3 pos;
        pos = getOriginAgent();
        pos.mV[VX] += x * mSurfacep->getMetersPerGrid();
        pos.mV[VY] += y * mSurfacep->getMetersPerGrid();
        pos.mV[VZ] = *(mDataZ + point_offset);
        return pos;
}

LLVector2 LLSurfacePatch::getTexCoords(const U32 x, const U32 y) const
{
        U32 surface_stride = mSurfacep->getGridsPerEdge();
        U32 point_offset = x + y*surface_stride;
        LLVector3 pos, rel_pos;
        pos = getOriginAgent();
        pos.mV[VX] += x * mSurfacep->getMetersPerGrid();
        pos.mV[VY] += y * mSurfacep->getMetersPerGrid();
        pos.mV[VZ] = *(mDataZ + point_offset);
        rel_pos = pos - mSurfacep->getOriginAgent();
        rel_pos *= 1.f/surface_stride;
        return LLVector2(rel_pos.mV[VX], rel_pos.mV[VY]);
}


void LLSurfacePatch::eval(const U32 x, const U32 y, const U32 stride, LLVector3 *vertex, LLVector3 *normal,
                                                  LLVector2 *tex0, LLVector2 *tex1)
{
        if (!mSurfacep || !mSurfacep->getRegion())
        {
                return; // failsafe
        }
        
        U32 surface_stride = mSurfacep->getGridsPerEdge();
        U32 point_offset = x + y*surface_stride;

        *normal = getNormal(x, y);

        LLVector3 pos_agent = getOriginAgent();
        pos_agent.mV[VX] += x * mSurfacep->getMetersPerGrid();
        pos_agent.mV[VY] += y * mSurfacep->getMetersPerGrid();
        pos_agent.mV[VZ]  = *(mDataZ + point_offset);
        *vertex     = pos_agent;

        LLVector3 rel_pos = pos_agent - mSurfacep->getOriginAgent();
        LLVector3 tex_pos = rel_pos * (1.f/surface_stride);
        tex0->mV[0]  = tex_pos.mV[0];
        tex0->mV[1]  = tex_pos.mV[1];
        tex1->mV[0] = mSurfacep->getRegion()->getCompositionXY(llfloor(mOriginRegion.mV[0])+x, llfloor(mOriginRegion.mV[1])+y);

        const F32 xyScale = 4.9215f*7.f; //0.93284f;
        const F32 xyScaleInv = (1.f / xyScale)*(0.2222222222f);

        F32 vec[3] = {
                                        fmod((F32)(mOriginGlobal.mdV[0] + x)*xyScaleInv, 256.f),
                                        fmod((F32)(mOriginGlobal.mdV[1] + y)*xyScaleInv, 256.f),
                                        0.f
                                };
        F32 rand_val = llclamp(noise2(vec)* 0.75f + 0.5f, 0.f, 1.f);
        tex1->mV[1] = rand_val;


}


void LLSurfacePatch::calcNormal(const U32 x, const U32 y, const U32 stride)
{
        U32 patch_width = mSurfacep->mPVArray.mPatchWidth;
        U32 surface_stride = mSurfacep->getGridsPerEdge();

        const F32 mpg = mSurfacep->getMetersPerGrid() * stride;

        S32 poffsets[2][2][2];
        poffsets[0][0][0] = x - stride;
        poffsets[0][0][1] = y - stride;

        poffsets[0][1][0] = x - stride;
        poffsets[0][1][1] = y + stride;

        poffsets[1][0][0] = x + stride;
        poffsets[1][0][1] = y - stride;

        poffsets[1][1][0] = x + stride;
        poffsets[1][1][1] = y + stride;

        const LLSurfacePatch *ppatches[2][2];

        // LLVector3 p1, p2, p3, p4;

        ppatches[0][0] = this;
        ppatches[0][1] = this;
        ppatches[1][0] = this;
        ppatches[1][1] = this;

        U32 i, j;
        for (i = 0; i < 2; i++)
        {
                for (j = 0; j < 2; j++)
                {
                        if (poffsets[i][j][0] < 0)
                        {
                                if (!ppatches[i][j]->getNeighborPatch(WEST))
                                {
                                        poffsets[i][j][0] = 0;
                                }
                                else
                                {
                                        poffsets[i][j][0] += patch_width;
                                        ppatches[i][j] = ppatches[i][j]->getNeighborPatch(WEST);
                                }
                        }
                        if (poffsets[i][j][1] < 0)
                        {
                                if (!ppatches[i][j]->getNeighborPatch(SOUTH))
                                {
                                        poffsets[i][j][1] = 0;
                                }
                                else
                                {
                                        poffsets[i][j][1] += patch_width;
                                        ppatches[i][j] = ppatches[i][j]->getNeighborPatch(SOUTH);
                                }
                        }
                        if (poffsets[i][j][0] >= (S32)patch_width)
                        {
                                if (!ppatches[i][j]->getNeighborPatch(EAST))
                                {
                                        poffsets[i][j][0] = patch_width - 1;
                                }
                                else
                                {
                                        poffsets[i][j][0] -= patch_width;
                                        ppatches[i][j] = ppatches[i][j]->getNeighborPatch(EAST);
                                }
                        }
                        if (poffsets[i][j][1] >= (S32)patch_width)
                        {
                                if (!ppatches[i][j]->getNeighborPatch(NORTH))
                                {
                                        poffsets[i][j][1] = patch_width - 1;
                                }
                                else
                                {
                                        poffsets[i][j][1] -= patch_width;
                                        ppatches[i][j] = ppatches[i][j]->getNeighborPatch(NORTH);
                                }
                        }
                }
        }

        LLVector3 p00(-mpg,-mpg,
                                  *(ppatches[0][0]->mDataZ
                                  + poffsets[0][0][0]
                                  + poffsets[0][0][1]*surface_stride));
        LLVector3 p01(-mpg,+mpg,
                                  *(ppatches[0][1]->mDataZ
                                  + poffsets[0][1][0]
                                  + poffsets[0][1][1]*surface_stride));
        LLVector3 p10(+mpg,-mpg,
                                  *(ppatches[1][0]->mDataZ
                                  + poffsets[1][0][0]
                                  + poffsets[1][0][1]*surface_stride));
        LLVector3 p11(+mpg,+mpg,
                                  *(ppatches[1][1]->mDataZ
                                  + poffsets[1][1][0]
                                  + poffsets[1][1][1]*surface_stride));

        LLVector3 c1 = p11 - p00;
        LLVector3 c2 = p01 - p10;

        LLVector3 normal = c1;
        normal %= c2;
        normal.normVec();

        *(mDataNorm + surface_stride * y + x) = normal;
}

const LLVector3 &LLSurfacePatch::getNormal(const U32 x, const U32 y) const
{
        U32 surface_stride = mSurfacep->getGridsPerEdge();
        return *(mDataNorm + surface_stride * y + x);
}


void LLSurfacePatch::updateCameraDistanceRegion(const LLVector3 &pos_region)
{
        LLVector3 dv = pos_region;
        dv -= mCenterRegion;
        mVisInfo.mDistance = llmax(0.f, (F32)(dv.magVec() - mRadius));
}

F32 LLSurfacePatch::getDistance() const
{
        return mVisInfo.mDistance;
}


// Called when a patch has changed its height field
// data.
void LLSurfacePatch::updateVerticalStats() 
{
        if (!mDirtyZStats)
        {
                return;
        }

        U32 grids_per_patch_edge = mSurfacep->getGridsPerPatchEdge();
        U32 grids_per_edge = mSurfacep->getGridsPerEdge();
        F32 meters_per_grid = mSurfacep->getMetersPerGrid();

        U32 i, j, k;
        F32 z, total;

        z = *(mDataZ);

        mMinZ = z;
        mMaxZ = z;

        k = 0;
        total = 0.0f;

        // Iterate to +1 because we need to do the edges correctly.
        for (j=0; j<(grids_per_patch_edge+1); j++) 
        {
                for (i=0; i<(grids_per_patch_edge+1); i++) 
                {
                        z = *(mDataZ + i + j*grids_per_edge);

                        if (z < mMinZ)
                        {
                                mMinZ = z;
                        }
                        if (z > mMaxZ)
                        {
                                mMaxZ = z;
                        }
                        total += z;
                        k++;
                }
        }
        mMeanZ = total / (F32) k;
        mCenterRegion.mV[VZ] = 0.5f * (mMinZ + mMaxZ);

        LLVector3 diam_vec(meters_per_grid*grids_per_patch_edge,
                                                meters_per_grid*grids_per_patch_edge,
                                                mMaxZ - mMinZ);
        mRadius = diam_vec.magVec() * 0.5f;

        mSurfacep->mMaxZ = llmax(mMaxZ, mSurfacep->mMaxZ);
        mSurfacep->mMinZ = llmin(mMinZ, mSurfacep->mMinZ);
        mSurfacep->mHasZData = TRUE;
        mSurfacep->getRegion()->calculateCenterGlobal();

        if (mVObjp)
        {
                mVObjp->dirtyPatch();
        }
        mDirtyZStats = FALSE;
}


void LLSurfacePatch::updateNormals() 
{
        if (mSurfacep->mType == 'w')
        {
                return;
        }
        U32 grids_per_patch_edge = mSurfacep->getGridsPerPatchEdge();
        U32 grids_per_edge = mSurfacep->getGridsPerEdge();

        BOOL dirty_patch = FALSE;

        U32 i, j;
        // update the east edge
        if (mNormalsInvalid[EAST] || mNormalsInvalid[NORTHEAST] || mNormalsInvalid[SOUTHEAST])
        {
                for (j = 0; j <= grids_per_patch_edge; j++)
                {
                        calcNormal(grids_per_patch_edge, j, 2);
                        calcNormal(grids_per_patch_edge - 1, j, 2);
                        calcNormal(grids_per_patch_edge - 2, j, 2);
                }

                dirty_patch = TRUE;
        }

        // update the north edge
        if (mNormalsInvalid[NORTHEAST] || mNormalsInvalid[NORTH] || mNormalsInvalid[NORTHWEST])
        {
                for (i = 0; i <= grids_per_patch_edge; i++)
                {
                        calcNormal(i, grids_per_patch_edge, 2);
                        calcNormal(i, grids_per_patch_edge - 1, 2);
                        calcNormal(i, grids_per_patch_edge - 2, 2);
                }

                dirty_patch = TRUE;
        }

        // update the west edge
        if (mNormalsInvalid[NORTHWEST] || mNormalsInvalid[WEST] || mNormalsInvalid[SOUTHWEST])
        {
                for (j = 0; j < grids_per_patch_edge; j++)
                {
                        calcNormal(0, j, 2);
                        calcNormal(1, j, 2);
                }
                dirty_patch = TRUE;
        }

        // update the south edge
        if (mNormalsInvalid[SOUTHWEST] || mNormalsInvalid[SOUTH] || mNormalsInvalid[SOUTHEAST])
        {
                for (i = 0; i < grids_per_patch_edge; i++)
                {
                        calcNormal(i, 0, 2);
                        calcNormal(i, 1, 2);
                }
                dirty_patch = TRUE;
        }

        // Invalidating the northeast corner is different, because depending on what the adjacent neighbors are,
        // we'll want to do different things.
        if (mNormalsInvalid[NORTHEAST])
        {
                if (!getNeighborPatch(NORTHEAST))
                {
                        if (!getNeighborPatch(NORTH))
                        {
                                if (!getNeighborPatch(EAST))
                                {
                                        // No north or east neighbors.  Pull from the diagonal in your own patch.
                                        *(mDataZ + grids_per_patch_edge + grids_per_patch_edge*grids_per_edge) =
                                                *(mDataZ + grids_per_patch_edge - 1 + (grids_per_patch_edge - 1)*grids_per_edge);
                                }
                                else
                                {
                                        if (getNeighborPatch(EAST)->getHasReceivedData())
                                        {
                                                // East, but not north.  Pull from your east neighbor's northwest point.
                                                *(mDataZ + grids_per_patch_edge + grids_per_patch_edge*grids_per_edge) =
                                                        *(getNeighborPatch(EAST)->mDataZ + (grids_per_patch_edge - 1)*grids_per_edge);
                                        }
                                        else
                                        {
                                                *(mDataZ + grids_per_patch_edge + grids_per_patch_edge*grids_per_edge) =
                                                        *(mDataZ + grids_per_patch_edge - 1 + (grids_per_patch_edge - 1)*grids_per_edge);
                                        }
                                }
                        }
                        else
                        {
                                // We have a north.
                                if (getNeighborPatch(EAST))
                                {
                                        // North and east neighbors, but not northeast.
                                        // Pull from diagonal in your own patch.
                                        *(mDataZ + grids_per_patch_edge + grids_per_patch_edge*grids_per_edge) =
                                                *(mDataZ + grids_per_patch_edge - 1 + (grids_per_patch_edge - 1)*grids_per_edge);
                                }
                                else
                                {
                                        if (getNeighborPatch(NORTH)->getHasReceivedData())
                                        {
                                                // North, but not east.  Pull from your north neighbor's southeast corner.
                                                *(mDataZ + grids_per_patch_edge + grids_per_patch_edge*grids_per_edge) =
                                                        *(getNeighborPatch(NORTH)->mDataZ + (grids_per_patch_edge - 1));
                                        }
                                        else
                                        {
                                                *(mDataZ + grids_per_patch_edge + grids_per_patch_edge*grids_per_edge) =
                                                        *(mDataZ + grids_per_patch_edge - 1 + (grids_per_patch_edge - 1)*grids_per_edge);
                                        }
                                }
                        }
                }
                else if (getNeighborPatch(NORTHEAST)->mSurfacep != mSurfacep)
                {
                        if (
                                (!getNeighborPatch(NORTH) || (getNeighborPatch(NORTH)->mSurfacep != mSurfacep))
                                &&
                                (!getNeighborPatch(EAST) || (getNeighborPatch(EAST)->mSurfacep != mSurfacep)))
                        {
                                *(mDataZ + grids_per_patch_edge + grids_per_patch_edge*grids_per_edge) =
                                                                                *(getNeighborPatch(NORTHEAST)->mDataZ);
                        }
                }
                else
                {
                        // We've got a northeast patch in the same surface.
                        // The z and normals will be handled by that patch.
                }
                calcNormal(grids_per_patch_edge, grids_per_patch_edge, 2);
                calcNormal(grids_per_patch_edge, grids_per_patch_edge - 1, 2);
                calcNormal(grids_per_patch_edge - 1, grids_per_patch_edge, 2);
                calcNormal(grids_per_patch_edge - 1, grids_per_patch_edge - 1, 2);
                dirty_patch = TRUE;
        }

        // update the middle normals
        if (mNormalsInvalid[MIDDLE])
        {
                for (j=2; j < grids_per_patch_edge - 2; j++)
                {
                        for (i=2; i < grids_per_patch_edge - 2; i++)
                        {
                                calcNormal(i, j, 2);
                        }
                }
                dirty_patch = TRUE;
        }

        if (dirty_patch)
        {
                mSurfacep->dirtySurfacePatch(this);
        }

        for (i = 0; i < 9; i++)
        {
                mNormalsInvalid[i] = FALSE;
        }
}

void LLSurfacePatch::updateEastEdge()
{
        U32 grids_per_patch_edge = mSurfacep->getGridsPerPatchEdge();
        U32 grids_per_edge = mSurfacep->getGridsPerEdge();

        U32 j, k;
        F32 *west_surface, *east_surface;

        if (!getNeighborPatch(EAST))
        {
                west_surface = mDataZ + grids_per_patch_edge;
                east_surface = mDataZ + grids_per_patch_edge - 1;
        }
        else if (mConnectedEdge & EAST_EDGE)
        {
                west_surface = mDataZ + grids_per_patch_edge;
                east_surface = getNeighborPatch(EAST)->mDataZ;
        }
        else
        {
                return;
        }

        // If patchp is on the east edge of its surface, then we update the east
        // side buffer
        for (j=0; j < grids_per_patch_edge; j++)
        {
                k = j * grids_per_edge;
                *(west_surface + k) = *(east_surface + k);      // update buffer Z
        }
}


void LLSurfacePatch::updateNorthEdge()
{
        U32 grids_per_patch_edge = mSurfacep->getGridsPerPatchEdge();
        U32 grids_per_edge = mSurfacep->getGridsPerEdge();

        U32 i;
        F32 *south_surface, *north_surface;

        if (!getNeighborPatch(NORTH))
        {
                south_surface = mDataZ + grids_per_patch_edge*grids_per_edge;
                north_surface = mDataZ + (grids_per_patch_edge - 1) * grids_per_edge;
        }
        else if (mConnectedEdge & NORTH_EDGE)
        {
                south_surface = mDataZ + grids_per_patch_edge*grids_per_edge;
                north_surface = getNeighborPatch(NORTH)->mDataZ;
        }
        else
        {
                return;
        }

        // Update patchp's north edge ...
        for (i=0; i<grids_per_patch_edge; i++)
        {
                *(south_surface + i) = *(north_surface + i);    // update buffer Z
        }
}


BOOL LLSurfacePatch::updateTexture()
{
        if (mSTexUpdate)                //  Update texture as needed
        {
                F32 meters_per_grid = getSurface()->getMetersPerGrid();
                F32 grids_per_patch_edge = (F32)getSurface()->getGridsPerPatchEdge();

                if ((!getNeighborPatch(EAST) || getNeighborPatch(EAST)->getHasReceivedData())
                        && (!getNeighborPatch(WEST) || getNeighborPatch(WEST)->getHasReceivedData())
                        && (!getNeighborPatch(SOUTH) || getNeighborPatch(SOUTH)->getHasReceivedData())
                        && (!getNeighborPatch(NORTH) || getNeighborPatch(NORTH)->getHasReceivedData()))
                {
                        LLViewerRegion *regionp = getSurface()->getRegion();
                        LLVector3d origin_region = getOriginGlobal() - getSurface()->getOriginGlobal();

                        // Have to figure out a better way to deal with these edge conditions...
                        LLVLComposition* comp = regionp->getComposition();
                        if (!mHeightsGenerated)
                        {
                                F32 patch_size = meters_per_grid*(grids_per_patch_edge+1);
                                if (comp->generateHeights((F32)origin_region[VX], (F32)origin_region[VY],
                                                                                  patch_size, patch_size))
                                {
                                        mHeightsGenerated = TRUE;
                                }
                                else
                                {
                                        return FALSE;
                                }
                        }
                        
                        if (comp->generateComposition())
                        {
                                if (mVObjp)
                                {
                                        mVObjp->dirtyGeom();
                                }
                                updateCompositionStats();
                                F32 tex_patch_size = meters_per_grid*grids_per_patch_edge;
                                if (comp->generateTexture((F32)origin_region[VX], (F32)origin_region[VY],
                                                                                  tex_patch_size, tex_patch_size))
                                {
                                        mSTexUpdate = FALSE;

                                        // Also generate the water texture
                                        mSurfacep->generateWaterTexture((F32)origin_region.mdV[VX], (F32)origin_region.mdV[VY],
                                                                                                        tex_patch_size, tex_patch_size);
                                        return TRUE;
                                }
                        }
                }
                return FALSE;
        }
        else
        {
                return TRUE;
        }
}


void LLSurfacePatch::dirtyZ()
{
        mSTexUpdate = TRUE;

        // Invalidate all normals in this patch
        U32 i;
        for (i = 0; i < 9; i++)
        {
                mNormalsInvalid[i] = TRUE;
        }

        // Invalidate normals in this and neighboring patches
        for (i = 0; i < 8; i++)
        {
                if (getNeighborPatch(i))
                {
                        getNeighborPatch(i)->mNormalsInvalid[gDirOpposite[i]] = TRUE;
                        getNeighborPatch(i)->dirty();
                        if (i < 4)
                        {
                                getNeighborPatch(i)->mNormalsInvalid[gDirAdjacent[gDirOpposite[i]][0]] = TRUE;
                                getNeighborPatch(i)->mNormalsInvalid[gDirAdjacent[gDirOpposite[i]][1]] = TRUE;
                        }
                }
        }

        dirty();
        mLastUpdateTime = gFrameTime;
}


const U64 &LLSurfacePatch::getLastUpdateTime() const
{
        return mLastUpdateTime;
}

F32 LLSurfacePatch::getMaxZ() const
{
        return mMaxZ;
}

F32 LLSurfacePatch::getMinZ() const
{
        return mMinZ;
}

void LLSurfacePatch::setOriginGlobal(const LLVector3d &origin_global)
{
        mOriginGlobal = origin_global;

        LLVector3 origin_region;
        origin_region.setVec(mOriginGlobal - mSurfacep->getOriginGlobal());

        mOriginRegion = origin_region;
        mCenterRegion.mV[VX] = origin_region.mV[VX] + 0.5f*mSurfacep->getGridsPerPatchEdge()*mSurfacep->getMetersPerGrid();
        mCenterRegion.mV[VY] = origin_region.mV[VY] + 0.5f*mSurfacep->getGridsPerPatchEdge()*mSurfacep->getMetersPerGrid();

        mVisInfo.mbIsVisible = FALSE;
        mVisInfo.mDistance = 512.0f;
        mVisInfo.mRenderLevel = 0;
        mVisInfo.mRenderStride = mSurfacep->getGridsPerPatchEdge();
        
}

void LLSurfacePatch::connectNeighbor(LLSurfacePatch *neighbor_patchp, const U32 direction)
{
        llassert(neighbor_patchp);
        mNormalsInvalid[direction] = TRUE;
        neighbor_patchp->mNormalsInvalid[gDirOpposite[direction]] = TRUE;

        setNeighborPatch(direction, neighbor_patchp);
        neighbor_patchp->setNeighborPatch(gDirOpposite[direction], this);

        if (EAST == direction)
        {
                mConnectedEdge |= EAST_EDGE;
                neighbor_patchp->mConnectedEdge |= WEST_EDGE;
        }
        else if (NORTH == direction)
        {
                mConnectedEdge |= NORTH_EDGE;
                neighbor_patchp->mConnectedEdge |= SOUTH_EDGE;
        }
        else if (WEST == direction)
        {
                mConnectedEdge |= WEST_EDGE;
                neighbor_patchp->mConnectedEdge |= EAST_EDGE;
        }
        else if (SOUTH == direction)
        {
                mConnectedEdge |= SOUTH_EDGE;
                neighbor_patchp->mConnectedEdge |= NORTH_EDGE;
        }
}

void LLSurfacePatch::updateVisibility()
{
        if (mVObjp.isNull())
        {
                return;
        }

        const F32 DEFAULT_DELTA_ANGLE   = (0.15f);
        U32 old_render_stride, max_render_stride;
        U32 new_render_level;
        F32 stride_per_distance = DEFAULT_DELTA_ANGLE / mSurfacep->getMetersPerGrid();
        U32 grids_per_patch_edge = mSurfacep->getGridsPerPatchEdge();

        // sphere in frustum on global coordinates
        if (gCamera->sphereInFrustum(mCenterRegion + mSurfacep->getOriginAgent(), mRadius) )
        {
                // We now need to calculate the render stride based on patchp's distance 
                // from LLCamera render_stride is governed by a relation something like this...
                //
                //                       delta_angle * patch.distance
                // render_stride <=  ----------------------------------------
                //                           mMetersPerGrid
                //
                // where 'delta_angle' is the desired solid angle of the average polgon on a patch.
                //
                // Any render_stride smaller than the RHS would be 'satisfactory'.  Smaller 
                // strides give more resolution, but efficiency suggests that we use the largest 
                // of the render_strides that obey the relation.  Flexibility is achieved by 
                // modulating 'delta_angle' until we have an acceptable number of triangles.
        
                old_render_stride = mVisInfo.mRenderStride;

                // Calculate the render_stride using information in agent
                max_render_stride = lltrunc(mVisInfo.mDistance * stride_per_distance);
                max_render_stride = llmin(max_render_stride , 2*grids_per_patch_edge);

                // We only use render_strides that are powers of two, so we use look-up tables to figure out
                // the render_level and corresponding render_stride
                new_render_level = mVisInfo.mRenderLevel = mSurfacep->getRenderLevel(max_render_stride);
                mVisInfo.mRenderStride = mSurfacep->getRenderStride(new_render_level);

                if ((mVisInfo.mRenderStride != old_render_stride)) 
                        // The reason we check !mbIsVisible is because non-visible patches normals 
                        // are not updated when their data is changed.  When this changes we can get 
                        // rid of mbIsVisible altogether.
                {
                        if (mVObjp)
                        {
                                mVObjp->dirtyGeom();
                                if (getNeighborPatch(WEST))
                                {
                                        getNeighborPatch(WEST)->mVObjp->dirtyGeom();
                                }
                                if (getNeighborPatch(SOUTH))
                                {
                                        getNeighborPatch(SOUTH)->mVObjp->dirtyGeom();
                                }
                        }
                }
                mVisInfo.mbIsVisible = TRUE;
        }
        else
        {
                mVisInfo.mbIsVisible = FALSE;
        }
}


const LLVector3d &LLSurfacePatch::getOriginGlobal() const
{
        return mOriginGlobal;
}

LLVector3 LLSurfacePatch::getOriginAgent() const
{
        return gAgent.getPosAgentFromGlobal(mOriginGlobal);
}

BOOL LLSurfacePatch::getVisible() const
{
        return mVisInfo.mbIsVisible;
}

U32 LLSurfacePatch::getRenderStride() const
{
        return mVisInfo.mRenderStride;
}

S32 LLSurfacePatch::getRenderLevel() const
{
        return mVisInfo.mRenderLevel;
}

void LLSurfacePatch::setHasReceivedData()
{
        mHasReceivedData = TRUE;
}

BOOL LLSurfacePatch::getHasReceivedData() const
{
        return mHasReceivedData;
}

const LLVector3 &LLSurfacePatch::getCenterRegion() const
{
        return mCenterRegion;
}


void LLSurfacePatch::updateCompositionStats()
{
        LLViewerLayer *vlp = mSurfacep->getRegion()->getComposition();

        F32 x, y, width, height, mpg, min, mean, max;

        LLVector3 origin = getOriginAgent() - mSurfacep->getOriginAgent();
        mpg = mSurfacep->getMetersPerGrid();
        x = origin.mV[VX];
        y = origin.mV[VY];
        width = mpg*(mSurfacep->getGridsPerPatchEdge()+1);
        height = mpg*(mSurfacep->getGridsPerPatchEdge()+1);

        mean = 0.f;
        min = vlp->getValueScaled(x, y);
        max= min;
        U32 count = 0;
        F32 i, j;
        for (j = 0; j < height; j += mpg)
        {
                for (i = 0; i < width; i += mpg)
                {
                        F32 comp = vlp->getValueScaled(x + i, y + j);
                        mean += comp;
                        min = llmin(min, comp);
                        max = llmax(max, comp);
                        count++;
                }
        }
        mean /= count;

        mMinComposition = min;
        mMeanComposition = mean;
        mMaxComposition = max;
}

F32 LLSurfacePatch::getMeanComposition() const
{
        return mMeanComposition;
}

F32 LLSurfacePatch::getMinComposition() const
{
        return mMinComposition;
}

F32 LLSurfacePatch::getMaxComposition() const
{
        return mMaxComposition;
}

void LLSurfacePatch::setNeighborPatch(const U32 direction, LLSurfacePatch *neighborp)
{
        mNeighborPatches[direction] = neighborp;
        mNormalsInvalid[direction] = TRUE;
        if (direction < 4)
        {
                mNormalsInvalid[gDirAdjacent[direction][0]] = TRUE;
                mNormalsInvalid[gDirAdjacent[direction][1]] = TRUE;
        }
}

LLSurfacePatch *LLSurfacePatch::getNeighborPatch(const U32 direction) const
{
        return mNeighborPatches[direction];
}

void LLSurfacePatch::clearVObj()
{
        mVObjp = NULL;
}

---