[PATCH v2] d3dx9: Simplify math in D3DXSphereBoundProbe

[A]

On 08/07/2020 10:31, Alex Henrie wrote:
> Signed-off-by: Alex Henrie <alexhenrie24 at gmail.com>
> ---
> v2: Calculating b isn't actually necessary at all.
> ---
>   dlls/d3dx9_36/mesh.c | 7 ++-----
>   1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/dlls/d3dx9_36/mesh.c b/dlls/d3dx9_36/mesh.c
> index 5e0bb98efc..381d19a2ee 100644
> --- a/dlls/d3dx9_36/mesh.c
> +++ b/dlls/d3dx9_36/mesh.c
> @@ -2413,16 +2413,13 @@ BOOL WINAPI D3DXSphereBoundProbe(const D3DXVECTOR3 *pcenter, float radius,
>           const D3DXVECTOR3 *prayposition, const D3DXVECTOR3 *praydirection)
>   {
>       D3DXVECTOR3 difference;
> -    FLOAT a, b, c, d;
> +    FLOAT a, c;
>   
>       a = D3DXVec3LengthSq(praydirection);
>       if (!D3DXVec3Subtract(&difference, prayposition, pcenter)) return FALSE;
> -    b = D3DXVec3Dot(&difference, praydirection);
>       c = D3DXVec3LengthSq(&difference) - radius * radius;
> -    d = b * b - a * c;
>   
> -    if ( ( d <= 0.0f ) || ( sqrt(d) <= b ) ) return FALSE;
> -    return TRUE;
> +    return ( a * c < 0 );
>   }
>   
>   /*************************************************************************

It doesn't make much sense to me. You're ignoring the direction of the 
ray. From what I could tell, it seems like you rearranged the right hand 
side of the "or" operator in the existing code, while ignoring the left 
hand side.

Regards,

Ariel