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matrix: remove a divide in look_at

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This commit is contained in:
Danny Robson 2016-10-11 20:56:41 +11:00
parent ced088f6b8
commit a1666a179b
1 changed files with 8 additions and 5 deletions
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13
matrix.cpp
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@ -261,16 +261,19 @@ template <size_t S, typename T>
matrix4<T>
matrix<S,T>::perspective (T fov, T aspect, range<T> Z)
{
T f = std::tan (fov / 2);
CHECK_GE (Z.min, 0);
CHECK_GE (Z.max, 0);
T tx = 1 / (f * aspect);
T ty = 1 / f;
T f = 1 / std::tan (fov / 2);
T x = f / aspect;
T y = f;
T z1 = (Z.max + Z.min) / (Z.min - Z.max);
T z2 = (2 * Z.max * Z.min) / (Z.min - Z.max);
return { {
{ tx, 0, 0, 0 },
{ 0, ty, 0, 0 },
{ x, 0, 0, 0 },
{ 0, y, 0, 0 },
{ 0, 0, z1, z2 },
{ 0, 0, -1, 0 }
} };