khanat-opennel-code/code/ryzom/client/src/decal.cpp
2013-02-18 13:22:03 +01:00

649 lines
21 KiB
C++

// Ryzom - MMORPG Framework <http://dev.ryzom.com/projects/ryzom/>
// Copyright (C) 2010 Winch Gate Property Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#include "stdpch.h"
#include "decal.h"
//
#include "nel/3d/shadow_map.h"
#include "nel/3d/texture_file.h"
#include "nel/3d/scene.h"
#include "nel/3d/driver_user.h"
#include "nel/3d/landscape.h"
#include "nel/3d/landscape_model.h"
#include "nel/3d/landscape_user.h"
#include "nel/3d/scene_user.h"
#include "nel/3d/texture_user.h"
//
// TMP TMP
#include "nel/3d/texture_mem.h"
//
#include "nel/misc/aabbox.h"
#include "nel/misc/vector_2f.h"
#include "nel/misc/plane.h"
//
#include "global.h"
//
#include "interface_v3/interface_manager.h"
using namespace NL3D;
using namespace NLMISC;
CDecalRenderList DecalRenderList;
extern uint SkipFrame;
NL3D::CVertexBuffer CDecal::_VB;
bool CDecal::_VBInitialized = false;
static const char *DecalAttenuationVertexProgramCode =
"!!VP1.0 \n\
DP4 o[HPOS].x, c[0], v[0]; #transform vertex in view space \n\
DP4 o[HPOS].y, c[1], v[0]; \n\
DP4 o[HPOS].z, c[2], v[0]; \n\
DP4 o[HPOS].w, c[3], v[0]; \n\
# transform texcoord 0 \n\
DP4 o[TEX0].x, c[4], v[0]; \n\
DP4 o[TEX0].y, c[5], v[0]; \n\
#compute distance from camera \n\
ADD R0, v[0], -c[6]; \n\
DP3 R0.x, R0, R0; \n\
RSQ R0.x, R0.x; \n\
RCP R0.x, R0.x; \n\
MUL o[COL0].xyz, c[8], v[3]; \n\
#compute attenuation with distance \n\
MAD R0.w, R0.x, c[7].x, c[7].y; \n\
# clamp in [0, 1] \n\
MIN R0.w, R0.w, c[7].w; \n\
MAX R0.w, R0.w, c[7].z; \n\
#compute bottom blend \n\
MAD R1.x, v[0].z, c[11].x, c[11].y; \n\
MIN R1.x, R1.x, c[7].w; \n\
MAX R1.x, R1.x, c[7].z; \n\
MUL R0.w, R1.x, R0.w; \n\
#compute top blend \n\
MAD R1.x, v[0].z, c[11].z, c[11].w; \n\
MIN R1.x, R1.x, c[7].w; \n\
MAX R1.x, R1.x, c[7].z; \n\
MUL R0.w, R1.x, R0.w; \n\
#apply vertex alpha \n\
MUL o[COL0].w, v[3], R0.w; \n\
END \n";
static NL3D::CVertexProgram DecalAttenuationVertexProgram(DecalAttenuationVertexProgramCode);
typedef CShadowPolyReceiver::CRGBAVertex CRGBAVertex;
// ****************************************************************************
CDecal::CDecal()
{
_ShadowMap = new CShadowMap(&(((CSceneUser *) Scene)->getScene().getRenderTrav().getShadowMapManager()));
_Material.initUnlit();
_Diffuse = CRGBA::White;
_Emissive = CRGBA::Black;
//
_Material.setBlend(true);
_Material.setSrcBlend(CMaterial::srcalpha);
_Material.setDstBlend(CMaterial::invsrcalpha);
_Material.setZWrite(false);
_Material.setDoubleSided(true);
// diffuse color applied at first stage
_Material.texEnvOpRGB(0, CMaterial::Modulate);
_Material.texEnvArg0RGB(0, CMaterial::Texture, CMaterial::SrcColor);
_Material.texEnvArg1RGB(0, CMaterial::Diffuse, CMaterial::SrcColor);
_Material.texEnvOpAlpha(0, CMaterial::Modulate);
_Material.texEnvArg0Alpha(0, CMaterial::Diffuse, CMaterial::SrcAlpha);
_Material.texEnvArg1Alpha(0, CMaterial::Texture, CMaterial::SrcAlpha);
//
_Material.texEnvOpRGB(1, CMaterial::Add);
_Material.texEnvArg0RGB(1, CMaterial::Previous, CMaterial::SrcColor);
_Material.texEnvArg1RGB(1, CMaterial::Constant, CMaterial::SrcColor);
_Material.texEnvOpAlpha(1, CMaterial::Modulate);
_Material.texEnvArg0Alpha(1, CMaterial::Previous, CMaterial::SrcAlpha);
_Material.texEnvArg1Alpha(1, CMaterial::Constant, CMaterial::SrcAlpha);
//
setEmissive(CRGBA::Black);
setDiffuse(CRGBA::White);
//
_Material.setAlphaTest(true);
_Material.setAlphaTestThreshold(1.f / 255.f);
//
_Touched = true;
_ClipDownFacing = false;
_WorldMatrix.get(_WorldMatrixFlat);
setWorldMatrix(_WorldMatrix);
//
_BottomBlendZMin = -10100.f;
_BottomBlendZMax = -10000.f;
_TopBlendZMin = 10000.f;
_TopBlendZMax = 10100.f;
}
// ****************************************************************************
void CDecal::setCustomUVMatrix(bool on, const NLMISC::CMatrix &matrix)
{
if (_CustomUVMatrix.set(on, matrix))
{
_Touched = true;
}
}
// ****************************************************************************
const std::string &CDecal::getTextureFileName() const
{
CTextureFile *tf = dynamic_cast<CTextureFile *>(_Material.getTexture(0));
if (tf) return tf->getFileName();
static std::string emptyString;
return emptyString;
}
// ****************************************************************************
void CDecal::setupMaterialColor()
{
_Material.texConstantColor(1, NLMISC::CRGBA(_Emissive.R, _Emissive.G, _Emissive.B, _Diffuse.A));
}
// ****************************************************************************
void CDecal::setEmissive(NLMISC::CRGBA emissive)
{
_Emissive = emissive;
setupMaterialColor();
}
// ****************************************************************************
void CDecal::setDiffuse(NLMISC::CRGBA diffuse)
{
_Diffuse = diffuse;
setupMaterialColor();
}
// ****************************************************************************
CRGBA CDecal::getDiffuse() const
{
return _Diffuse;
}
// ****************************************************************************
CDecal::~CDecal()
{
delete _ShadowMap;
}
// ****************************************************************************
void CDecal::setTexture(const std::string &fileName, bool clampU, bool clampV, bool filtered)
{
if (getTextureFileName() != fileName)
{
CInterfaceManager *im = CInterfaceManager::getInstance();
CViewRenderer &vr = *CViewRenderer::getInstance();
UTexture *tex = vr.getGlobalTexture(fileName);
if (tex != NULL)
{
_Material.setTexture(0, (dynamic_cast<NL3D::CTextureUser *>(tex))->getITexture());
}
else
{
_Material.setTexture(0, fileName.empty() ? NULL : new CTextureFile(fileName));
}
if (_Material.getTexture(0))
{
_Material.getTexture(0)->setUploadFormat(ITexture::RGBA8888); // don't want ugly dxtc mipmaps for most decals
}
}
if (_Material.getTexture(0))
{
_Material.getTexture(0)->setWrapS(clampU ? ITexture::Clamp : ITexture::Repeat);
_Material.getTexture(0)->setWrapT(clampV ? ITexture::Clamp : ITexture::Repeat);
if (filtered)
{
_Material.getTexture(0)->setFilterMode(ITexture::Linear , ITexture::LinearMipMapLinear);
}
else
{
_Material.getTexture(0)->setFilterMode(ITexture::Nearest, ITexture::NearestMipMapOff);
}
_Material.setTexture(1, _Material.getTexture(0));
}
else
{
_Material.setTexture(1, NULL);
}
}
// ****************************************************************************
void CDecal::setWorldMatrix(const NLMISC::CMatrix &matrix)
{
float newMat[16];
matrix.get(newMat);
if (std::equal(newMat, newMat + 16, _WorldMatrixFlat)) return;
_WorldMatrix = matrix;
_WorldMatrix.get(_WorldMatrixFlat);
_InvertedWorldMatrix = matrix.inverted();
_Touched = true;
const float bboxHeight = 10000.f;
static const NLMISC::CVector corners[8] =
{
CVector(0.f, 0.f, - bboxHeight),
CVector(1.f, 0.f, - bboxHeight),
CVector(0.f, 1.f, - bboxHeight),
CVector(1.f, 1.f, - bboxHeight),
CVector(0.f, 0.f, bboxHeight),
CVector(1.f, 0.f, bboxHeight),
CVector(0.f, 1.f, bboxHeight),
CVector(1.f, 1.f, bboxHeight),
};
for(uint k = 0; k < 8; ++k)
{
_ClipCorners[k] = _WorldMatrix * corners[k];
}
}
// ****************************************************************************
bool CDecal::clipFront(const NLMISC::CPlane &p) const
{
for(uint k = 0; k < 8; ++k)
{
if (p * _ClipCorners[k] <= 0.f) return false;
}
return true;
}
// ****************************************************************************
void CDecal::setWorldMatrixForArrow(const NLMISC::CVector2f &start, const NLMISC::CVector2f &end, float halfWidth)
{
CMatrix matrix;
CVector I = CVector(end.x, end.y, 0.f) - CVector(start.x, start.y, 0.f);
CVector J = 2.f * halfWidth * CVector::K ^ I.normed();
matrix.setRot(I, J, CVector::K);
matrix.setPos(start - 0.5f * J);
setWorldMatrix(matrix);
}
// ****************************************************************************
void CDecal::setWorldMatrixForSpot(const NLMISC::CVector2f &pos, float radius, float angleInRadians)
{
CMatrix matrix;
matrix.rotateZ(angleInRadians);
matrix.setScale(2.f * radius);
matrix.setPos(pos - radius * CVector2f(1.f, 1.f));
setWorldMatrix(matrix);
}
NLMISC::CVector r2MaskOffset(1.f / 4.f, 1.f / 4.f, 0.f);
// ****************************************************************************
void CDecal::renderTriCache(NL3D::IDriver &drv, NL3D::CShadowPolyReceiver &/* receiver */, bool useVertexProgram)
{
if (_TriCache.empty()) return;
if (!_VBInitialized)
{
_VB.setPreferredMemory(CVertexBuffer::AGPVolatile, false);
_VB.setVertexFormat(CVertexBuffer::PositionFlag|CVertexBuffer::PrimaryColorFlag);
_VBInitialized = true;
}
CMatrix modelMat;
modelMat.setPos(_RefPosition);
drv.setupModelMatrix(modelMat);
if (useVertexProgram)
{
{
CVertexBufferReadWrite vba;
_VB.setNumVertices((uint32)_TriCache.size());
_VB.lock(vba);
memcpy(vba.getVertexCoordPointer(), &_TriCache[0], sizeof(CRGBAVertex) * _TriCache.size());
}
drv.activeVertexBuffer(_VB);
drv.setConstantMatrix(0, NL3D::IDriver::ModelViewProjection, NL3D::IDriver::Identity);
drv.setConstant(4, _WorldToUVMatrix[0][0], _WorldToUVMatrix[1][0], _WorldToUVMatrix[2][0], _WorldToUVMatrix[3][0]);
drv.setConstant(5, _WorldToUVMatrix[0][1], _WorldToUVMatrix[1][1], _WorldToUVMatrix[2][1], _WorldToUVMatrix[3][1]);
drv.setConstant(8, _Diffuse.R * (1.f / 255.f), _Diffuse.G * (1.f / 255.f), _Diffuse.B * (1.f / 255.f), 1.f);
const NLMISC::CVector &camPos = MainCam.getMatrix().getPos();
drv.setConstant(6, camPos.x - _RefPosition.x, camPos.y - _RefPosition.y, camPos.z - _RefPosition.z, 1.f);
// bottom & top blend
float bottomBlendScale = 1.f / favoid0(_BottomBlendZMax - _BottomBlendZMin);
float topBlendScale = 1.f / favoid0(_TopBlendZMin - _TopBlendZMax);
drv.setConstant(11, bottomBlendScale, bottomBlendScale * (_RefPosition.z - _BottomBlendZMin),
topBlendScale, topBlendScale * (_RefPosition.z - _TopBlendZMax));
//
static volatile bool wantSimpleMat = false;
if (wantSimpleMat)
{
static CMaterial simpleMat;
static volatile bool disableStencil = false;
if (disableStencil)
{
drv.enableStencilTest(false);
}
simpleMat.initUnlit();
simpleMat.setTexture(0, _Material.getTexture(0));
simpleMat.texEnvOpRGB(0, CMaterial::Replace);
simpleMat.texEnvArg0RGB(0, CMaterial::Constant, CMaterial::SrcColor);
simpleMat.setDoubleSided(true);
simpleMat.texConstantColor(0, CRGBA::White);
drv.renderRawTriangles(simpleMat, 0, (uint32)_TriCache.size() / 3);
IDriver::TPolygonMode pm = drv.getPolygonMode();
drv.setPolygonMode(IDriver::Line);
simpleMat.texConstantColor(0, CRGBA::Red);
drv.renderRawTriangles(simpleMat, 0, (uint32)_TriCache.size() / 3);
drv.setPolygonMode(pm);
}
else
{
drv.renderRawTriangles(_Material, 0, (uint32)_TriCache.size() / 3);
}
}
else
{
{
CVertexBufferReadWrite vba;
_VB.setNumVertices((uint32)_TriCache.size());
_VB.lock(vba);
NLMISC::CRGBA col = _Diffuse;
if (drv.getVertexColorFormat()==CVertexBuffer::TBGRA)
{
std::swap(col.R, col.B);
}
CRGBAVertex *dest = (CRGBAVertex *) vba.getVertexCoordPointer();
const CRGBAVertex *destEnd = dest + _TriCache.size();
const CRGBAVertex *srcVert = &_TriCache[0];
const NLMISC::CVector camPos = MainCam.getMatrix().getPos() - _RefPosition;
float scale = 255.f * CDecalRenderList::getInstance()._DistScale;
float bias = 255.f * CDecalRenderList::getInstance()._DistBias;
float bottomBlendScale = 1.f / favoid0(_BottomBlendZMax - _BottomBlendZMin);
float bottomBlendBias = bottomBlendScale * (_RefPosition.z - _BottomBlendZMin);
do
{
dest->V = srcVert->V;
float dist = (camPos - srcVert->V).norm();
float intensity = scale * dist + bias;
float bottomBlend = srcVert->V.z * bottomBlendScale + bottomBlendBias;
clamp(bottomBlend, 0.f, 1.f);
clamp(intensity, 0.f, 255.f);
intensity *= bottomBlend;
col.A = (uint8) (((uint16) intensity * (uint16) srcVert->Color.A) >> 8);
dest->Color = col;
++dest;
++srcVert;
}
while (dest != destEnd);
}
drv.activeVertexBuffer(_VB);
static volatile bool wantSimpleMat2 = false;
if (wantSimpleMat2)
{
static CMaterial simpleMat2;
simpleMat2.initUnlit();
simpleMat2.setDoubleSided(true);
drv.renderRawTriangles(simpleMat2, 0, (uint32)_TriCache.size() / 3);
}
else
{
drv.renderRawTriangles(_Material, 0, (uint32)_TriCache.size() / 3);
}
}
}
// ****************************************************************************
void CDecal::render(NL3D::UDriver &/* drv */,
NL3D::CShadowPolyReceiver &receiver,
const std::vector<CPlane> &worldPyramid,
const std::vector<NLMISC::CVector> &pyramidCorners,
bool useVertexProgram
)
{
const NLMISC::CVector &camPos = MainCam.getMatrix().getPos();
if ((camPos - _LastCamPos).norm() >= 4.f)
{
_Touched = true;
}
if (_Touched)
{
_LastCamPos = camPos;
}
// if out of only 1 plane, entirely out.
for(sint i=0;i<(sint)worldPyramid.size();i++)
{
if (clipFront(worldPyramid[i])) return;
}
// do finer clip
uint inside = 0;
for(uint l = 0; l < pyramidCorners.size(); ++l)
{
NLMISC::CVector localCorner = _InvertedWorldMatrix * pyramidCorners[l];
if (localCorner.x >= 0.f) inside |= 1;
if (localCorner.x <= 1.f) inside |= 2;
if (localCorner.y >= 0.f) inside |= 4;
if (localCorner.y <= 1.f) inside |= 8;
}
if(inside != 0xf) return;
// must setup attenuation texture each frame
/*
_Material.enableUserTexMat(1, true);
_Material.setTexCoordGen(1, true);
_Material.setTexCoordGenMode(1, CMaterial::TexCoordGenObjectSpace);
// object is in world space
float scale = 1.f / tileNear;
CMatrix attenMat;
attenMat.setScale(CVector(0.5f * scale, tileNear, 0.f));
attenMat.setPos(CVector(-0.5f * (1.f - camPos.x * scale), -0.5f * (1.f - camPos.y * scale), 0.f));
_Material.setUserTexMat(1, attenMat);
*/
//
if (!_Touched)
{
NL3D::IDriver *drvInternal = ((CDriverUser *) Driver)->getDriver();
renderTriCache(*drvInternal, receiver, useVertexProgram);
return;
}
//
float tileNear = Landscape->getTileNear();
//
nlassert(_ShadowMap);
_ShadowMap->LocalClipPlanes.resize(4);
CVector corners[4] =
{
_WorldMatrix * CVector(0.f, 1.f, 0.f),
_WorldMatrix * CVector(1.f, 1.f, 0.f),
_WorldMatrix * CVector(1.f, 0.f, 0.f),
_WorldMatrix * CVector(0.f, 0.f, 0.f)
};
CAABBox bbox;
_ShadowMap->LocalBoundingBox.setMinMax(corners[0], corners[1]);
_ShadowMap->LocalBoundingBox.extend(corners[2]);
_ShadowMap->LocalBoundingBox.extend(corners[3]);
for(uint k = 0; k < 4; ++k)
{
_ShadowMap->LocalClipPlanes[k].make(corners[k], corners[(k + 1) & 3], corners[k] + (corners[(k + 1) & 3] - corners[k]).norm() * CVector::K);
_ShadowMap->LocalClipPlanes[k].invert();
}
_RefPosition = MainCam.getMatrix().getPos();
// set uv matrix to match the world matrix
// matrix to map (x, y ) = (0, 0) to (u, v) = (0, 1) & (x, y ) = (0, 1) to (u, v) = (0, 0) in local decal space
CMatrix reverseUVMatrix;
reverseUVMatrix.setRot(CVector::I, -CVector::J, CVector::K);
reverseUVMatrix.setPos(CVector::J);
CMatrix worldToUVMatrix = _CustomUVMatrix.On ? _CustomUVMatrix.Matrix :
(_TextureMatrix * reverseUVMatrix * _InvertedWorldMatrix);
CMatrix refPosMatrix;
refPosMatrix.setPos(_RefPosition);
worldToUVMatrix = worldToUVMatrix * refPosMatrix;
worldToUVMatrix.get((float *) _WorldToUVMatrix);
// stage 0
if (useVertexProgram)
{
_Material.enableUserTexMat(0, false);
}
else
{
_Material.enableUserTexMat(0, true);
_Material.setTexCoordGen(0, true);
_Material.setTexCoordGenMode(0, CMaterial::TexCoordGenObjectSpace);
_Material.setUserTexMat(0, worldToUVMatrix);
}
//
//
static NLMISC::CPolygon clipPoly;
static NLMISC::CPolygon2D clipPoly2D;
clipPoly.Vertices.resize(4);
std::copy(corners, corners + 4, clipPoly.Vertices.begin());
// clip with by "near tiles" for better selection (avoid unwanted wrapping during triangle selection ...)
CPlane planes[4];
planes[0].make(CVector::J, camPos + tileNear * CVector::J),
planes[1].make(-CVector::J, camPos - tileNear * CVector::J),
planes[2].make(CVector::I, camPos + tileNear * CVector::I),
planes[3].make(-CVector::I, camPos - tileNear * CVector::I);
uint numVerts = (uint)clipPoly.Vertices.size();
clipPoly2D.Vertices.resize(numVerts);
for (uint k = 0; k < numVerts; ++k)
{
clipPoly2D.Vertices[k].set(clipPoly.Vertices[k].x, clipPoly.Vertices[k].y);
}
NL3D::IDriver *drvInternal = ((CDriverUser *) Driver)->getDriver();
// rebuild the triangle cache
if (SkipFrame == 0) // don't update just after a tp because landscape hasn't been updated yet ...
{
_Touched = false;
}
// compute tris near the camera to avoid precision z-preision problems due to huge translation in the world matrix)
receiver.computeClippedTrisWithPolyClip(_ShadowMap, CVector::Null, - _RefPosition, clipPoly2D, _TriCache, _ClipDownFacing);
_Material.setZBias(-0.06f);
renderTriCache(*drvInternal, receiver, useVertexProgram);
}
// ****************************************************************************
void CDecalRenderList::renderAllDecals()
{
if (_Empty) return;
if( !Landscape)
{
return;
}
Driver->enableFog(false);
MainCam.buildCameraPyramid(_WorldCamPyramid, false);
MainCam.buildCameraPyramidCorners(_WorldCamPyramidCorners, false);
Driver->setModelMatrix(CMatrix::Identity);
CLandscapeModel *landscapeModel = ((CLandscapeUser *) Landscape)->getLandscape();
CShadowPolyReceiver &shadowPolyReceiver = landscapeModel->Landscape.getShadowPolyReceiver();
//
float maxDist = Landscape->getTileNear() * 0.9f;
const float threshold = 0.8f; // ratio over the whole dist at which the fade out begins
float factor = 1.f / (1.f - threshold);
_DistScale = - factor / maxDist;
_DistBias = factor;
//
bool useVertexProgram = false;
NL3D::IDriver *drvInternal = ((CDriverUser *) Driver)->getDriver();
//
static volatile bool forceNoVertexProgram = false;
if (drvInternal->isVertexProgramSupported() && !forceNoVertexProgram)
{
//drvInternal->setConstantMatrix(0, NL3D::IDriver::ModelViewProjection, NL3D::IDriver::Identity);
drvInternal->setConstant(7, _DistScale, _DistBias, 0.f, 1.f);
useVertexProgram = true;
drvInternal->activeVertexProgram(&DecalAttenuationVertexProgram);
}
else
{
drvInternal->activeVertexProgram(NULL);
}
for(uint k = 0; k < DECAL_NUM_PRIORITIES; ++k)
{
std::vector<CDecal::TRefPtr> &renderList = _RenderList[k];
for(uint l = 0; l < renderList.size(); ++l)
{
if (renderList[l])
{
renderList[l]->render(*Driver, shadowPolyReceiver, _WorldCamPyramid, _WorldCamPyramidCorners, useVertexProgram);
}
}
}
if (useVertexProgram)
{
drvInternal->activeVertexProgram(NULL);
}
}
// ****************************************************************************
void CDecalRenderList::clearRenderList()
{
for(uint k = 0; k < DECAL_NUM_PRIORITIES; ++k)
{
_RenderList[k].clear();
}
_Empty = true;
}
// ****************************************************************************
void CDecal::addToRenderList(uint priority /*=0*/)
{
if( !Landscape)
{
return;
}
nlassert(priority < DECAL_NUM_PRIORITIES);
CDecalRenderList &drl = CDecalRenderList::getInstance();
drl._RenderList[priority].push_back(this);
drl._Empty = false;
}
// ****************************************************************************
bool CDecal::contains(const NLMISC::CVector2f &pos) const
{
CVector posIn = _InvertedWorldMatrix * CVector(pos.x, pos.y, 0.f);
return posIn.x >= 0.f && posIn.x <= 1.f && posIn.y >= 0.f && posIn.y <= 1.f;
}
// ****************************************************************************
void CDecal::setClipDownFacing(bool clipDownFacing)
{
if (clipDownFacing != _ClipDownFacing)
{
_Touched = true;
_ClipDownFacing = clipDownFacing;
}
}
// ****************************************************************************
void CDecal::setBottomBlend(float zMin, float zMax)
{
if (zMin > zMax) std::swap(zMin, zMax);
_BottomBlendZMin = zMin;
_BottomBlendZMax = zMax;
}
// ****************************************************************************
void CDecal::setTopBlend(float zMin, float zMax)
{
if (zMin > zMax) std::swap(zMin, zMax);
_TopBlendZMin = zMin;
_TopBlendZMax = zMax;
}