OpenSpace/modules/globebrowsing/other/patchcoverageprovider.cpp

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* OpenSpace                                                                             *
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* Copyright (c) 2014-2016                                                               *
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#include <modules/globebrowsing/other/patchcoverageprovider.h>

#include <ghoul/logging/logmanager.h>

#include <glm/glm.hpp>

namespace {
    const std::string _loggerCat = "PatchCoverageProvider";
}

namespace openspace {

    PatchCoverageProvider::PatchCoverageProvider(
        std::shared_ptr<TileProvider> tileProvider,
        Geodetic2 sizeLevel0,
        Geodetic2 offsetLevel0,
        int depth)
        : _tileProvider(tileProvider)
        , _sizeLevel0(sizeLevel0)
        , _offsetLevel0(offsetLevel0)
        , _depth(depth)
    {
    }

    PatchCoverageProvider::~PatchCoverageProvider(){

    }

    GeodeticTileIndex PatchCoverageProvider::getTileIndex(const GeodeticPatch& patch) {
        // Calculate the level of the index depanding on the size of the incoming patch.
        // The level is as big as possible (as far down as possible) but it can't be
        // too big since at maximum four tiles should be used to cover a patch
        int level = log2(static_cast<int>(glm::max(
            _sizeLevel0.lat / (patch.size().lat),
            _sizeLevel0.lon / (patch.size().lon))));
        
        // If the depth is not big enough, the level must be clamped.
        level = glm::min(level, _depth);
        
        // Calculate the index in x y where the tile should be positioned
        Geodetic2 tileSize = _sizeLevel0 / pow(2, level);
        Geodetic2 nw = patch.northWestCorner();
        glm::ivec2 tileIndexXY =
            (nw.toLonLatVec2() - _offsetLevel0.toLonLatVec2()) / tileSize.toLonLatVec2();

        // Flip y since indices increase from top to bottom
        tileIndexXY.y = pow(2, level) - 1 - tileIndexXY.y;

        // Create the tileindex
        GeodeticTileIndex tileIndex = { tileIndexXY.x, tileIndexXY.y, level };
        return tileIndex;
    }

    glm::mat3 PatchCoverageProvider::getUvTransformationPatchToTile(
        GeodeticPatch patch,
        const GeodeticTileIndex& tileIndex)
    {
        GeodeticPatch tile(tileIndex);
        return getUvTransformationPatchToTile(patch, tile);
    }

    glm::mat3 PatchCoverageProvider::getUvTransformationPatchToTile(
        GeodeticPatch patch,
        GeodeticPatch tile)
    {
        Vec2 posDiff =
            patch.southWestCorner().toLonLatVec2() -
            tile.southWestCorner().toLonLatVec2();

        glm::mat3 invTileScale = glm::mat3(
        {	1 / (tile.size().lon),	        0,								0,
            0,								1 / (tile.size().lat),          0,
            0,								0,								1 });

        glm::mat3 globalTranslation = glm::mat3(
        {	1,			0,			0,
            0,			1,			0,
            posDiff.x,	posDiff.y,	1 });

        glm::mat3 patchScale = glm::mat3(
        {	(patch.halfSize().lon * 2),	0,								0,
            0,							(patch.halfSize().lat * 2),		0,
            0,							0,								1 });

        return invTileScale * globalTranslation * patchScale;
    }

    PatchCoverage PatchCoverageProvider::getCoverage(GeodeticPatch patch)
    {
        static const int numTilesInCoverageX = 2;
        static const int numTilesInCoverageY = 2;
        PatchCoverage patchCoverageToReturn;

        for (int y = 0; y < numTilesInCoverageY; y++)
        {
            for (int x = 0; x < numTilesInCoverageX; x++)
            {
                int linearIdx = x + y * numTilesInCoverageX;
                GeodeticTileIndex tileIndex = getTileIndex(patch);
                // Offset tileIndex
                tileIndex.x += x;
                tileIndex.y += y;

                int numLevelsToLoop = tileIndex.level;
                // Start at the highest level and go down if the texture don't exist
                for (int j = numLevelsToLoop; j >= 0; j--)
                {
                    // Try if the texture exists
                    std::shared_ptr<Texture> tile = _tileProvider->getTile(tileIndex);
                    if (tile == nullptr)
                    { // If it doesn't exist, go down a level
                        tileIndex.x /= 2;
                        tileIndex.y /= 2;
                        tileIndex.level -= 1;
                    }
                    else
                    { // A texture was found, put it in the data structure to return
                        patchCoverageToReturn.textureTransformPairs[linearIdx].first =
                            tile;
                        patchCoverageToReturn.textureTransformPairs[linearIdx].second =
                            getUvTransformationPatchToTile(patch, tileIndex);
                    }
                }
                // If the texture still doesn't exist put a temporary texture
                if (patchCoverageToReturn.textureTransformPairs[linearIdx].first == nullptr)
                {
                    patchCoverageToReturn.textureTransformPairs[linearIdx].first =
                        _tileProvider->getTemporaryTexture();
                    patchCoverageToReturn.textureTransformPairs[linearIdx].second =
                        glm::mat3(1);
                }
            }
        }
        
        return patchCoverageToReturn;
    }

}  // namespace openspace