bd028579
 易尊强
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var LN2 = Math.log(2);
function determinant(rows, rank, rowStart, rowMask, colMask, detCache) {
var cacheKey = rowMask + '-' + colMask;
var fullRank = rows.length;
if (detCache.hasOwnProperty(cacheKey)) {
return detCache[cacheKey];
}
if (rank === 1) {
var colStart = Math.round(Math.log(((1 << fullRank) - 1) & ~colMask) / LN2);
return rows[rowStart][colStart];
}
var subRowMask = rowMask | (1 << rowStart);
var subRowStart = rowStart + 1;
while (rowMask & (1 << subRowStart)) {
subRowStart++;
}
var sum = 0;
for (var j = 0, colLocalIdx = 0; j < fullRank; j++) {
var colTag = 1 << j;
if (!(colTag & colMask)) {
sum += (colLocalIdx % 2 ? -1 : 1) * rows[rowStart][j]
* determinant(rows, rank - 1, subRowStart, subRowMask, colMask | colTag, detCache);
colLocalIdx++;
}
}
detCache[cacheKey] = sum;
return sum;
}
export function buildTransformer(src, dest) {
var mA = [
[src[0], src[1], 1, 0, 0, 0, -dest[0] * src[0], -dest[0] * src[1]],
[0, 0, 0, src[0], src[1], 1, -dest[1] * src[0], -dest[1] * src[1]],
[src[2], src[3], 1, 0, 0, 0, -dest[2] * src[2], -dest[2] * src[3]],
[0, 0, 0, src[2], src[3], 1, -dest[3] * src[2], -dest[3] * src[3]],
[src[4], src[5], 1, 0, 0, 0, -dest[4] * src[4], -dest[4] * src[5]],
[0, 0, 0, src[4], src[5], 1, -dest[5] * src[4], -dest[5] * src[5]],
[src[6], src[7], 1, 0, 0, 0, -dest[6] * src[6], -dest[6] * src[7]],
[0, 0, 0, src[6], src[7], 1, -dest[7] * src[6], -dest[7] * src[7]]
];
var detCache = {};
var det = determinant(mA, 8, 0, 0, 0, detCache);
if (det === 0) {
return;
}
var vh = [];
for (var i = 0; i < 8; i++) {
for (var j = 0; j < 8; j++) {
vh[j] == null && (vh[j] = 0);
vh[j] += ((i + j) % 2 ? -1 : 1)
* determinant(mA, 7, i === 0 ? 1 : 0, 1 << i, 1 << j, detCache)
/ det * dest[i];
}
}
return function (out, srcPointX, srcPointY) {
var pk = srcPointX * vh[6] + srcPointY * vh[7] + 1;
out[0] = (srcPointX * vh[0] + srcPointY * vh[1] + vh[2]) / pk;
out[1] = (srcPointX * vh[3] + srcPointY * vh[4] + vh[5]) / pk;
};
}
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