Terrain: create 4x4 terrain chunks per ESM::Cell to improve performance

Improves performance because the number of splatting layers per chunk is reduced, and finer grained frustum culling can be done.

components/esmterrain/storage.cpp

@@ -1,6 +1,7 @@
 #include "storage.hpp"
 
 #include <set>
+#include <iostream>
 
 #include <osg/Image>
 #include <osg/Plane>
@@ -34,19 +35,22 @@ namespace ESMTerrain
 
         osg::Vec2f origin = center - osg::Vec2f(size/2.f, size/2.f);
 
-        assert(origin.x() == (int) origin.x());
-        assert(origin.y() == (int) origin.y());
+        int cellX = static_cast<int>(std::floor(origin.x()));
+        int cellY = static_cast<int>(std::floor(origin.y()));
 
-        int cellX = static_cast<int>(origin.x());
-        int cellY = static_cast<int>(origin.y());
+        int startRow = (origin.x() - cellX) * ESM::Land::LAND_SIZE;
+        int startColumn = (origin.y() - cellY) * ESM::Land::LAND_SIZE;
+
+        int endRow = startRow + size * (ESM::Land::LAND_SIZE-1) + 1;
+        int endColumn = startColumn + size * (ESM::Land::LAND_SIZE-1) + 1;
 
         if (const ESM::Land::LandData *data = getLandData (cellX, cellY, ESM::Land::DATA_VHGT))
         {
             min = std::numeric_limits<float>::max();
             max = -std::numeric_limits<float>::max();
-            for (int row=0; row<ESM::Land::LAND_SIZE; ++row)
+            for (int row=startRow; row<endRow; ++row)
             {
-                for (int col=0; col<ESM::Land::LAND_SIZE; ++col)
+                for (int col=startColumn; col<endColumn; ++col)
                 {
                     float h = data->mHeights[col*ESM::Land::LAND_SIZE+row];
                     if (h > max)
@@ -143,11 +147,9 @@ namespace ESMTerrain
         size_t increment = 1 << lodLevel;
 
         osg::Vec2f origin = center - osg::Vec2f(size/2.f, size/2.f);
-        assert(origin.x() == (int) origin.x());
-        assert(origin.y() == (int) origin.y());
 
-        int startX = static_cast<int>(origin.x());
-        int startY = static_cast<int>(origin.y());
+        int startCellX = static_cast<int>(std::floor(origin.x()));
+        int startCellY = static_cast<int>(std::floor(origin.y()));
 
         size_t numVerts = static_cast<size_t>(size*(ESM::Land::LAND_SIZE - 1) / increment + 1);
 
@@ -162,10 +164,10 @@ namespace ESMTerrain
         float vertX = 0;
 
         float vertY_ = 0; // of current cell corner
-        for (int cellY = startY; cellY < startY + std::ceil(size); ++cellY)
+        for (int cellY = startCellY; cellY < startCellY + std::ceil(size); ++cellY)
         {
             float vertX_ = 0; // of current cell corner
-            for (int cellX = startX; cellX < startX + std::ceil(size); ++cellX)
+            for (int cellX = startCellX; cellX < startCellX + std::ceil(size); ++cellX)
             {
                 const ESM::Land::LandData *heightData = getLandData (cellX, cellY, ESM::Land::DATA_VHGT);
                 const ESM::Land::LandData *normalData = getLandData (cellX, cellY, ESM::Land::DATA_VNML);
@@ -175,18 +177,31 @@ namespace ESMTerrain
                 int colStart = 0;
                 // Skip the first row / column unless we're at a chunk edge,
                 // since this row / column is already contained in a previous cell
+                // This is only relevant if we're creating a chunk spanning multiple cells
                 if (colStart == 0 && vertY_ != 0)
                     colStart += increment;
                 if (rowStart == 0 && vertX_ != 0)
                     rowStart += increment;
 
+                // Only relevant for chunks smaller than (contained in) one cell
+                rowStart += (origin.x() - startCellX) * ESM::Land::LAND_SIZE;
+                colStart += (origin.y() - startCellY) * ESM::Land::LAND_SIZE;
+                int rowEnd = rowStart + std::min(1.f, size) * (ESM::Land::LAND_SIZE-1) + 1;
+                int colEnd = colStart + std::min(1.f, size) * (ESM::Land::LAND_SIZE-1) + 1;
+
                 vertY = vertY_;
-                for (int col=colStart; col<ESM::Land::LAND_SIZE; col += increment)
+                for (int col=colStart; col<colEnd; col += increment)
                 {
                     vertX = vertX_;
-                    for (int row=rowStart; row<ESM::Land::LAND_SIZE; row += increment)
+                    for (int row=rowStart; row<rowEnd; row += increment)
                     {
-                        int arrayIndex = col*ESM::Land::LAND_SIZE*3+row*3;
+                        int srcArrayIndex = col*ESM::Land::LAND_SIZE*3+row*3;
+
+                        assert(row >= 0 && row < ESM::Land::LAND_SIZE);
+                        assert(col >= 0 && col < ESM::Land::LAND_SIZE);
+
+                        assert (vertX < numVerts);
+                        assert (vertY < numVerts);
 
                         float height = -2048;
                         if (heightData)
@@ -200,7 +215,7 @@ namespace ESMTerrain
                         if (normalData)
                         {
                             for (int i=0; i<3; ++i)
-                                normal[i] = normalData->mNormals[arrayIndex+i];
+                                normal[i] = normalData->mNormals[srcArrayIndex+i];
 
                             normal.normalize();
                         }
@@ -222,7 +237,7 @@ namespace ESMTerrain
                         if (colourData)
                         {
                             for (int i=0; i<3; ++i)
-                                color[i] = colourData->mColours[arrayIndex+i] / 255.f;
+                                color[i] = colourData->mColours[srcArrayIndex+i] / 255.f;
                         }
                         else
                         {
@@ -305,8 +320,19 @@ namespace ESMTerrain
         // and interpolate the rest of the cell by hand? :/
 
         osg::Vec2f origin = chunkCenter - osg::Vec2f(chunkSize/2.f, chunkSize/2.f);
-        int cellX = static_cast<int>(origin.x());
-        int cellY = static_cast<int>(origin.y());
+        int cellX = static_cast<int>(std::floor(origin.x()));
+        int cellY = static_cast<int>(std::floor(origin.y()));
+
+        int realTextureSize = ESM::Land::LAND_TEXTURE_SIZE+1; // add 1 to wrap around next cell
+
+        int rowStart = (origin.x() - cellX) * realTextureSize;
+        int colStart = (origin.y() - cellY) * realTextureSize;
+        int rowEnd = rowStart + chunkSize * (realTextureSize-1) + 1;
+        int colEnd = colStart + chunkSize * (realTextureSize-1) + 1;
+
+        assert (rowStart >= 0 && colStart >= 0);
+        assert (rowEnd <= realTextureSize);
+        assert (colEnd <= realTextureSize);
 
         // Save the used texture indices so we know the total number of textures
         // and number of required blend maps
@@ -317,8 +343,15 @@ namespace ESMTerrain
         // So we're always adding _land_default.dds as the base layer here, even if it's not referenced in this cell.
         textureIndices.insert(std::make_pair(0,0));
 
-        for (int y=0; y<ESM::Land::LAND_TEXTURE_SIZE+1; ++y)
-            for (int x=0; x<ESM::Land::LAND_TEXTURE_SIZE+1; ++x)
+        /*
+        _________
+        | | | | - | | | | -
+        | | | | - | | | | -
+
+        */
+
+        for (int y=colStart; y<colEnd; ++y)
+            for (int x=rowStart; x<rowEnd; ++x)
             {
                 UniqueTextureId id = getVtexIndexAt(cellX, cellY, x, y);
                 textureIndices.insert(id);
@@ -342,7 +375,7 @@ namespace ESMTerrain
         int channels = pack ? 4 : 1;
 
         // Second iteration - create and fill in the blend maps
-        const int blendmapSize = ESM::Land::LAND_TEXTURE_SIZE+1;
+        const int blendmapSize = (realTextureSize-1) * chunkSize + 1;
 
         for (int i=0; i<numBlendmaps; ++i)
         {
@@ -356,7 +389,8 @@ namespace ESMTerrain
             {
                 for (int x=0; x<blendmapSize; ++x)
                 {
-                    UniqueTextureId id = getVtexIndexAt(cellX, cellY, x, y);
+                    UniqueTextureId id = getVtexIndexAt(cellX, cellY, x+rowStart, y+colStart);
+                    assert(textureIndicesMap.find(id) != textureIndicesMap.end());
                     int layerIndex = textureIndicesMap.find(id)->second;
                     int blendIndex = (pack ? static_cast<int>(std::floor((layerIndex - 1) / 4.f)) : layerIndex - 1);
                     int channel = pack ? std::max(0, (layerIndex-1) % 4) : 0;

components/terrain/buffercache.cpp

@@ -1,6 +1,7 @@
 #include "buffercache.hpp"
 
 #include <cassert>
+#include <iostream>
 
 #include <osg/PrimitiveSet>
 
@@ -208,6 +209,8 @@ namespace Terrain
     {
         unsigned int verts = mNumVerts;
 
+        std::cout << "getting index buffer for " << verts << std::endl;
+
         if (mIndexBufferMap.find(flags) != mIndexBufferMap.end())
         {
             return mIndexBufferMap[flags];

components/terrain/material.cpp

@@ -11,7 +11,7 @@ namespace Terrain
 {
 
     FixedFunctionTechnique::FixedFunctionTechnique(const std::vector<osg::ref_ptr<osg::Texture2D> >& layers,
-                                                   const std::vector<osg::ref_ptr<osg::Texture2D> >& blendmaps, int blendmapSize, float layerTileSize)
+                                                   const std::vector<osg::ref_ptr<osg::Texture2D> >& blendmaps, int blendmapScale, float layerTileSize)
     {
         bool firstLayer = true;
         int i=0;
@@ -36,7 +36,7 @@ namespace Terrain
 
                 // This is to map corner vertices directly to the center of a blendmap texel.
                 osg::Matrixf texMat;
-                float scale = (blendmapSize/(static_cast<float>(blendmapSize)+1.f));
+                float scale = (blendmapScale/(static_cast<float>(blendmapScale)+1.f));
                 texMat.preMultTranslate(osg::Vec3f(0.5f, 0.5f, 0.f));
                 texMat.preMultScale(osg::Vec3f(scale, scale, 1.f));
                 texMat.preMultTranslate(osg::Vec3f(-0.5f, -0.5f, 0.f));
@@ -67,10 +67,10 @@ namespace Terrain
     }
 
     Effect::Effect(const std::vector<osg::ref_ptr<osg::Texture2D> > &layers, const std::vector<osg::ref_ptr<osg::Texture2D> > &blendmaps,
-                   int blendmapSize, float layerTileSize)
+                   int blendmapScale, float layerTileSize)
         : mLayers(layers)
         , mBlendmaps(blendmaps)
-        , mBlendmapSize(blendmapSize)
+        , mBlendmapScale(blendmapScale)
         , mLayerTileSize(layerTileSize)
     {
         osg::ref_ptr<osg::Material> material (new osg::Material);
@@ -82,7 +82,7 @@ namespace Terrain
 
     bool Effect::define_techniques()
     {
-        addTechnique(new FixedFunctionTechnique(mLayers, mBlendmaps, mBlendmapSize, mLayerTileSize));
+        addTechnique(new FixedFunctionTechnique(mLayers, mBlendmaps, mBlendmapScale, mLayerTileSize));
 
         return true;
     }

components/terrain/material.hpp

@@ -19,7 +19,7 @@ namespace Terrain
     public:
         FixedFunctionTechnique(
                 const std::vector<osg::ref_ptr<osg::Texture2D> >& layers,
-                const std::vector<osg::ref_ptr<osg::Texture2D> >& blendmaps, int blendmapSize, float layerTileSize);
+                const std::vector<osg::ref_ptr<osg::Texture2D> >& blendmaps, int blendmapScale, float layerTileSize);
 
     protected:
         virtual void define_passes() {}
@@ -30,7 +30,7 @@ namespace Terrain
     public:
         Effect(
                 const std::vector<osg::ref_ptr<osg::Texture2D> >& layers,
-                const std::vector<osg::ref_ptr<osg::Texture2D> >& blendmaps, int blendmapSize, float layerTileSize);
+                const std::vector<osg::ref_ptr<osg::Texture2D> >& blendmaps, int blendmapScale, float layerTileSize);
 
         virtual bool define_techniques();
 
@@ -50,7 +50,7 @@ namespace Terrain
     private:
         std::vector<osg::ref_ptr<osg::Texture2D> > mLayers;
         std::vector<osg::ref_ptr<osg::Texture2D> > mBlendmaps;
-        int mBlendmapSize;
+        int mBlendmapScale;
         float mLayerTileSize;
     };
 

components/terrain/terraingrid.cpp

@@ -1,6 +1,8 @@
 #include "terraingrid.hpp"
 
 #include <memory>
+#include <osg/io_utils>
+#include <iostream>
 
 #include <components/resource/resourcesystem.hpp>
 #include <components/resource/texturemanager.hpp>
@@ -47,8 +49,10 @@ namespace Terrain
 TerrainGrid::TerrainGrid(osg::Group* parent, Resource::ResourceSystem* resourceSystem, osgUtil::IncrementalCompileOperation* ico,
                          Storage* storage, int nodeMask)
     : Terrain::World(parent, resourceSystem, ico, storage, nodeMask)
+    , mNumSplits(4)
     , mKdTreeBuilder(new osg::KdTreeBuilder)
 {
+    mCache = BufferCache((storage->getCellVertices()-1)/static_cast<float>(mNumSplits) + 1);
 }
 
 TerrainGrid::~TerrainGrid()
@@ -62,25 +66,39 @@ TerrainGrid::~TerrainGrid()
 class GridElement
 {
 public:
-    osg::ref_ptr<osg::PositionAttitudeTransform> mNode;
+    osg::ref_ptr<osg::Node> mNode;
 };
 
-void TerrainGrid::loadCell(int x, int y)
+osg::ref_ptr<osg::Node> TerrainGrid::buildTerrain (osg::Group* parent, float chunkSize, const osg::Vec2f& chunkCenter)
+{
+    if (chunkSize * mNumSplits > 1.f)
+    {
+        // keep splitting
+        osg::ref_ptr<osg::Group> group (new osg::Group);
+        if (parent)
+            parent->addChild(group);
+        std::cout << "splitting " << chunkSize << " " << std::endl;
+        float newChunkSize = chunkSize/2.f;
+        buildTerrain(group, newChunkSize, chunkCenter + osg::Vec2f(newChunkSize/2.f, newChunkSize/2.f));
+        buildTerrain(group, newChunkSize, chunkCenter + osg::Vec2f(newChunkSize/2.f, -newChunkSize/2.f));
+        buildTerrain(group, newChunkSize, chunkCenter + osg::Vec2f(-newChunkSize/2.f, newChunkSize/2.f));
+        buildTerrain(group, newChunkSize, chunkCenter + osg::Vec2f(-newChunkSize/2.f, -newChunkSize/2.f));
+        return group;
+    }
+    else
     {
-    if (mGrid.find(std::make_pair(x, y)) != mGrid.end())
-        return; // already loaded
-
-    osg::Vec2f center(x+0.5f, y+0.5f);
         float minH, maxH;
-    if (!mStorage->getMinMaxHeights(1, center, minH, maxH))
-        return; // no terrain defined
+        if (!mStorage->getMinMaxHeights(chunkSize, chunkCenter, minH, maxH))
+            return NULL; // no terrain defined
 
-    std::auto_ptr<GridElement> element (new GridElement);
+        std::cout << "creating " << chunkSize << " " << chunkCenter << std::endl;
 
-    osg::Vec2f worldCenter = center*mStorage->getCellWorldSize();
-    element->mNode = new osg::PositionAttitudeTransform;
-    element->mNode->setPosition(osg::Vec3f(worldCenter.x(), worldCenter.y(), 0.f));
-    mTerrainRoot->addChild(element->mNode);
+        osg::Vec2f worldCenter = chunkCenter*mStorage->getCellWorldSize();
+        osg::ref_ptr<osg::PositionAttitudeTransform> transform (new osg::PositionAttitudeTransform);
+        transform->setPosition(osg::Vec3f(worldCenter.x(), worldCenter.y(), 0.f));
+
+        if (parent)
+            parent->addChild(transform);
 
         osg::ref_ptr<osg::Vec3Array> positions (new osg::Vec3Array);
         osg::ref_ptr<osg::Vec3Array> normals (new osg::Vec3Array);
@@ -91,7 +109,7 @@ void TerrainGrid::loadCell(int x, int y)
         normals->setVertexBufferObject(vbo);
         colors->setVertexBufferObject(vbo);
 
-    mStorage->fillVertexBuffers(0, 1, center, positions, normals, colors);
+        mStorage->fillVertexBuffers(0, chunkSize, chunkCenter, positions, normals, colors);
 
         osg::ref_ptr<osg::Geometry> geometry (new osg::Geometry);
         geometry->setVertexArray(positions);
@@ -103,11 +121,11 @@ void TerrainGrid::loadCell(int x, int y)
         geometry->addPrimitiveSet(mCache.getIndexBuffer(0));
 
         // we already know the bounding box, so no need to let OSG compute it.
-    osg::Vec3f min(-0.5f*mStorage->getCellWorldSize(),
-                   -0.5f*mStorage->getCellWorldSize(),
+        osg::Vec3f min(-0.5f*mStorage->getCellWorldSize()*chunkSize,
+                       -0.5f*mStorage->getCellWorldSize()*chunkSize,
                        minH);
-    osg::Vec3f max (0.5f*mStorage->getCellWorldSize(),
-                       0.5f*mStorage->getCellWorldSize(),
+        osg::Vec3f max (0.5f*mStorage->getCellWorldSize()*chunkSize,
+                           0.5f*mStorage->getCellWorldSize()*chunkSize,
                            maxH);
         osg::BoundingBox bounds(min, max);
         geometry->setComputeBoundingBoxCallback(new StaticBoundingBoxCallback(bounds));
@@ -115,13 +133,10 @@ void TerrainGrid::loadCell(int x, int y)
         osg::ref_ptr<osg::Geode> geode (new osg::Geode);
         geode->addDrawable(geometry);
 
-    // build a kdtree to speed up intersection tests with the terrain
-    // Note, the build could be optimized using a custom kdtree builder, since we know that the terrain can be represented by a quadtree
-    geode->accept(*mKdTreeBuilder);
 
         std::vector<LayerInfo> layerList;
         std::vector<osg::ref_ptr<osg::Image> > blendmaps;
-    mStorage->getBlendmaps(1.f, center, false, blendmaps, layerList);
+        mStorage->getBlendmaps(chunkSize, chunkCenter, false, blendmaps, layerList);
 
         // For compiling textures, I don't think the osgFX::Effect does it correctly
         osg::ref_ptr<osg::Node> textureCompileDummy (new osg::Node);
@@ -152,18 +167,48 @@ void TerrainGrid::loadCell(int x, int y)
         for (unsigned int i=0; i<2; ++i)
             geometry->setTexCoordArray(i, mCache.getUVBuffer());
 
-    osg::ref_ptr<osgFX::Effect> effect (new Terrain::Effect(layerTextures, blendmapTextures, ESM::Land::LAND_TEXTURE_SIZE, ESM::Land::LAND_TEXTURE_SIZE));
+        float blendmapScale = ESM::Land::LAND_TEXTURE_SIZE*chunkSize;
+        osg::ref_ptr<osgFX::Effect> effect (new Terrain::Effect(layerTextures, blendmapTextures, blendmapScale, blendmapScale));
 
         effect->addCullCallback(new SceneUtil::LightListCallback);
 
+        transform->addChild(effect);
         effect->addChild(geode);
-    element->mNode->addChild(effect);
 
+        return transform;
+    }
+}
+
+void TerrainGrid::loadCell(int x, int y)
+{
+    if (mGrid.find(std::make_pair(x, y)) != mGrid.end())
+        return; // already loaded
+
+    osg::Vec2f center(x+0.5f, y+0.5f);
+
+    osg::ref_ptr<osg::Node> terrainNode = buildTerrain(NULL, 1.f, center);
+    if (!terrainNode)
+        return; // no terrain defined
+
+    std::auto_ptr<GridElement> element (new GridElement);
+    element->mNode = terrainNode;
+    mTerrainRoot->addChild(element->mNode);
+
+    /*
+    // build a kdtree to speed up intersection tests with the terrain
+    // Note, the build could be optimized using a custom kdtree builder, since we know that the terrain can be represented by a quadtree
+    geode->accept(*mKdTreeBuilder);
+    */
+
+
+    /*
     if (mIncrementalCompileOperation)
     {
         mIncrementalCompileOperation->add(geode);
         mIncrementalCompileOperation->add(textureCompileDummy);
     }
+    */
+
 
     mGrid[std::make_pair(x,y)] = element.release();
 }

components/terrain/terraingrid.hpp

@@ -1,6 +1,8 @@
 #ifndef COMPONENTS_TERRAIN_TERRAINGRID_H
 #define COMPONENTS_TERRAIN_TERRAINGRID_H
 
+#include <osg/Vec2f>
+
 #include "world.hpp"
 #include "material.hpp"
 
@@ -26,6 +28,11 @@ namespace Terrain
         virtual void unloadCell(int x, int y);
 
     private:
+        osg::ref_ptr<osg::Node> buildTerrain (osg::Group* parent, float chunkSize, const osg::Vec2f& chunkCenter);
+
+        // split each ESM::Cell into mNumSplits*mNumSplits terrain chunks
+        unsigned int mNumSplits;
+
         typedef std::map<std::pair<int, int>, GridElement*> Grid;
         Grid mGrid;