OOConvertCubeMapToLatLong.h File Reference

import "OOPixMap.h"

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Functions
OOPixMap	OOConvertCubeMapToLatLong (OOPixMap sourcePixMap, OOPixMapDimension height, BOOL leaveSpaceForMipMaps)

Function Documentation

OOConvertCubeMapToLatLong()

OOPixMap OOConvertCubeMapToLatLong	(	OOPixMap	sourcePixMap,
		OOPixMapDimension	height,
		BOOL	leaveSpaceForMipMaps )

Definition at line 37 of file OOConvertCubeMapToLatLong.m.

{
    if (!OOIsValidPixMap(sourcePixMap) || sourcePixMap.format != kOOPixMapRGBA || sourcePixMap.height != sourcePixMap.width * 6)
    {
        return kOONullPixMap;
    }
    
    NSCParameterAssert(height > 0);
    
    height *= 2;
    OOPixMapDimension width = height * 2;
    OOPixMap outPixMap = OOAllocatePixMap(width, height, 4, 0, 0);
    if (!OOIsValidPixMap(outPixMap))  return kOONullPixMap;
    
    OOPixMapDimension x, y;
    uint32_t *pixel = outPixMap.pixels;
    float fheight = height;
    float rheight = 1.0f / fheight;
    
    float halfSize = (sourcePixMap.width - 1) * 0.5f;
    uint8_t *srcBytes = sourcePixMap.pixels;
    
    // Build tables of sin/cos of longitude.
    float sinTable[width];
    float cosTable[width];
    for (x = 0; x < width; x++)
    {
        float lon = ((float)x * rheight) * kPiF;
        sinTable[x] = sin(lon);
        cosTable[x] = cos(lon);
    }
    
    for (y = 0; y < height; y++)
    {
        // Calcuate sin/cos of latitude.
        /*
            Clang static analyzer (Xcode 3.2.5 version, through to Xcode 4.4
            and freestanding checker-268 at least) says:
            "Assigned value is garbage or undefined."
            Memsetting sinTable to all-zeros moves this to the cosTable line.
            Since every value in each of those tables is in fact defined, this
            is an error in the analyzer.
            -- Ahruman 2011-01-25/2012-09-14
        */
        float cy = -sinTable[width * 3 / 4 - y];
        float lac = -cosTable[width * 3 / 4 - y];
        float ay = fabs(cy);
        
        for (x = 0; x < width; x++)
        {
            float cx = sinTable[x] * lac;
            float cz = cosTable[x] * lac;
            
            float ax = fabs(cx);
            float az = fabs(cz);
            
            // Y offset of start of this face in image.
            OOPixMapDimension yOffset;
            
            // Coordinates within selected face.
            float x, y, r;
            
            // Select source face.
            if (ax >= ay && ax >= az)
            {
                x = cz;
                y = -cy;
                r = ax;
                if (0.0f < cx)
                {
                    yOffset = 0;
                }
                else
                {
                    x = -x;
                    yOffset = 1;
                }
            }
            else if (ay >= ax && ay >= az)
            {
                x = cx;
                y = cz;
                r = ay;
                if (0.0f < cy)
                {
                    y = -y;
                    yOffset = 2;
                }
                else
                {
                    yOffset = 3;
                }
            }
            else
            {
                x = cx;
                y = -cy;
                r = az;
                if (0.0f < cz)
                {
                    x = -x;
                    yOffset = 5;
                }
                else
                {
                    yOffset = 4;
                }       
            }
            
            // Scale coordinates.
            r = 1.0f / r;
            OOPixMapDimension ix = (x * r + 1.0f) * halfSize;
            OOPixMapDimension iy = (y * r + 1.0f) * halfSize;
            
#ifndef NDEBUG
            assert(ix < sourcePixMap.width && iy < sourcePixMap.width);
#endif
            
            // Look up pixel.
            iy += sourcePixMap.width * yOffset;
            
            uint32_t *row = (uint32_t *)(srcBytes + iy * sourcePixMap.rowBytes);
            *pixel++ = row[ix];
        }
    }
    
    // Scale to half size for supersamplingness.
    return OOScalePixMap(outPixMap, width / 2, height / 2, leaveSpaceForMipMaps);
}

References OOPixMap::format, OOPixMap::height, kOONullPixMap, kOOPixMapRGBA, kPiF, OOAllocatePixMap(), OOIsValidPixMap(), OOScalePixMap(), OOPixMap::pixels, OOPixMap::rowBytes, OOPixMap::width, x, and y.

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