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Fix CImage::copyToScaling bug introduced in r5994.

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The change to the scaling code caused scaling to read outside of original image memory.
Was caused because scaling step factor was based on image-sizes, but has to be based on amount of scaling steps taking (off-by-one error).
Thanks @Maksym Hamarnyk for reporting that there was some problem.


git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6121 dfc29bdd-3216-0410-991c-e03cc46cb475
This commit is contained in:
cutealien 2020-06-14 20:42:30 +00:00
parent 05fb5bc776
commit 01a4f5d359
1 changed files with 12 additions and 4 deletions
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16
source/Irrlicht/CImage.cpp
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@ -216,13 +216,21 @@ void CImage::copyToScaling(void* target, u32 width, u32 height, ECOLOR_FORMAT fo
} }
} }
const f32 sourceXStep = (f32)Size.Width / (f32)width; // NOTE: Scaling is coded to keep the border pixels intact.
const f32 sourceYStep = (f32)Size.Height / (f32)height; // Alternatively we could for example work with first pixel being taken at half step-size.
// Then we have one more step here and it would be:
// sourceXStep = (f32)(Size.Width-1) / (f32)(width);
// And sx would start at 0.5f + sourceXStep / 2.f;
// Similar for y.
// As scaling is done without any antialiasing it doesn't matter too much which outermost pixels we use and keeping
// border pixels intact is probably mostly better (with AA the other solution would be more correct).
const f32 sourceXStep = width > 1 ? (f32)(Size.Width-1) / (f32)(width-1) : 0.f;
const f32 sourceYStep = height > 1 ? (f32)(Size.Height-1) / (f32)(height-1) : 0.f;
s32 yval=0, syval=0; s32 yval=0, syval=0;
f32 sy = 0.5f; // nearest pixel (used in float-int conversion below) f32 sy = 0.5f; // for rounding to nearest pixel
for (u32 y=0; y<height; ++y) for (u32 y=0; y<height; ++y)
{ {
f32 sx = 0.5f; // nearest pixel (used in float-int conversion below) f32 sx = 0.5f; // for rounding to nearest pixel
for (u32 x=0; x<width; ++x) for (u32 x=0; x<width; ++x)
{ {
CColorConverter::convert_viaFormat(Data+ syval + ((s32)sx)*BytesPerPixel, Format, 1, ((u8*)target)+ yval + (x*bpp), format); CColorConverter::convert_viaFormat(Data+ syval + ((s32)sx)*BytesPerPixel, Format, 1, ((u8*)target)+ yval + (x*bpp), format);