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private int[] imageSizeTemp = new int[1];
/** Helper for more precise computation of number of bytes that will
be touched by a pixel pack or unpack operation. */
private int imageSizeInBytes(int bytesPerElement,
int width, int height, int depth, boolean pack) {
int rowLength = 0;
int skipRows = 0;
int skipPixels = 0;
int alignment = 1;
int imageHeight = 0;
int skipImages = 0;
if (pack) {
glGetIntegerv(GL_PACK_ROW_LENGTH, imageSizeTemp, 0);
rowLength = imageSizeTemp[0];
glGetIntegerv(GL_PACK_SKIP_ROWS, imageSizeTemp, 0);
skipRows = imageSizeTemp[0];
glGetIntegerv(GL_PACK_SKIP_PIXELS, imageSizeTemp, 0);
skipPixels = imageSizeTemp[0];
glGetIntegerv(GL_PACK_ALIGNMENT, imageSizeTemp, 0);
alignment = imageSizeTemp[0];
if (depth > 1) {
glGetIntegerv(GL_PACK_IMAGE_HEIGHT, imageSizeTemp, 0);
imageHeight = imageSizeTemp[0];
glGetIntegerv(GL_PACK_SKIP_IMAGES, imageSizeTemp, 0);
skipImages = imageSizeTemp[0];
}
} else {
glGetIntegerv(GL_UNPACK_ROW_LENGTH, imageSizeTemp, 0);
rowLength = imageSizeTemp[0];
glGetIntegerv(GL_UNPACK_SKIP_ROWS, imageSizeTemp, 0);
skipRows = imageSizeTemp[0];
glGetIntegerv(GL_UNPACK_SKIP_PIXELS, imageSizeTemp, 0);
skipPixels = imageSizeTemp[0];
glGetIntegerv(GL_UNPACK_ALIGNMENT, imageSizeTemp, 0);
alignment = imageSizeTemp[0];
if (depth > 1) {
glGetIntegerv(GL_UNPACK_IMAGE_HEIGHT, imageSizeTemp, 0);
imageHeight = imageSizeTemp[0];
glGetIntegerv(GL_UNPACK_SKIP_IMAGES, imageSizeTemp, 0);
skipImages = imageSizeTemp[0];
}
}
// Try to deal somewhat correctly with potentially invalid values
width = Math.max(0, width );
height = Math.max(1, height); // min 1D
depth = Math.max(1, depth ); // min 1 * imageSize
skipRows = Math.max(0, skipRows);
skipPixels = Math.max(0, skipPixels);
alignment = Math.max(1, alignment);
skipImages = Math.max(0, skipImages);
imageHeight = ( imageHeight > 0 ) ? imageHeight : height;
rowLength = ( rowLength > 0 ) ? rowLength : width;
int rowLengthInBytes = rowLength * bytesPerElement;
if (alignment > 1) {
int padding = rowLengthInBytes % alignment;
if (padding > 0) {
rowLengthInBytes += alignment - padding;
}
}
/**
* skipPixels and skipRows is a static one time offset.
*
* skipImages and depth are in multiples of image size.
*
* rowlenght is the actual repeating offset
* to go from line n to line n+1 at the same x-axis position.
*/
int imageSize = imageHeight * rowLengthInBytes;
int skipOffset = skipImages * imageSize +
skipRows * rowLengthInBytes +
skipPixels * bytesPerElement;
return skipOffset + imageSize * depth;
}
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