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sw_engine raster: checking zero division while inverting the transform matrix

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In case the user has provided the transformation matrix, it is possible that
the inverse matrix does not exist.
This commit is contained in:
Mira Grudzinska 2021-02-03 14:00:35 +01:00 • committed by Hermet Park
parent 46f8945028
commit 6925f6c272
1 changed files with 8 additions and 2 deletions
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10
src/lib/sw_engine/tvgSwRaster.cpp
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@ -46,13 +46,15 @@ static uint32_t _argbJoin(uint8_t r, uint8_t g, uint8_t b, uint8_t a)
}
static void _inverse(const Matrix* transform, Matrix* invM)
static bool _inverse(const Matrix* transform, Matrix* invM)
{
// computes the inverse of a matrix m
auto det = transform->e11 * (transform->e22 * transform->e33 - transform->e32 * transform->e23) -
transform->e12 * (transform->e21 * transform->e33 - transform->e23 * transform->e31) +
transform->e13 * (transform->e21 * transform->e32 - transform->e22 * transform->e31);
if (fabsf(det) < FLT_EPSILON) return false;
auto invDet = 1 / det;
invM->e11 = (transform->e22 * transform->e33 - transform->e32 * transform->e23) * invDet;
@ -64,6 +66,8 @@ static void _inverse(const Matrix* transform, Matrix* invM)
invM->e31 = (transform->e21 * transform->e32 - transform->e31 * transform->e22) * invDet;
invM->e32 = (transform->e31 * transform->e12 - transform->e11 * transform->e32) * invDet;
invM->e33 = (transform->e11 * transform->e22 - transform->e21 * transform->e12) * invDet;
return true;
}
@ -832,7 +836,9 @@ bool rasterImage(SwSurface* surface, SwImage* image, const Matrix* transform, Sw
{
Matrix invTransform;
if (transform) _inverse(transform, &invTransform);
if (transform) {
if (!_inverse(transform, &invTransform)) return false;
}
else invTransform = {1, 0, 0, 0, 1, 0, 0, 0, 1};
auto translucent = _translucent(surface, opacity);