diff options
Diffstat (limited to 'src/maths/maths.h')
| -rw-r--r-- | src/maths/maths.h | 65 |
1 files changed, 31 insertions, 34 deletions
diff --git a/src/maths/maths.h b/src/maths/maths.h index 8e48435..e0d39d7 100644 --- a/src/maths/maths.h +++ b/src/maths/maths.h @@ -91,45 +91,42 @@ static inline quat quat_slerp(quat a, quat b, f32 percentage) { quat q1 = quat_normalise(b); // Compute the cosine of the angle between the two vectors. - f32 dot = quat_dot(q0, q1); - - // If the dot product is negative, slerp won't take - // the shorter path. Note that v1 and -v1 are equivalent when - // the negation is applied to all four components. Fix by - // reversing one quaternion. - if (dot < 0.0f) { - q1.x = -q1.x; - q1.y = -q1.y; - q1.z = -q1.z; - q1.w = -q1.w; - dot = -dot; - } + f32 dot = quat_dot(q0, q1); + + // If the dot product is negative, slerp won't take + // the shorter path. Note that v1 and -v1 are equivalent when + // the negation is applied to all four components. Fix by + // reversing one quaternion. + if (dot < 0.0f) { + q1.x = -q1.x; + q1.y = -q1.y; + q1.z = -q1.z; + q1.w = -q1.w; + dot = -dot; + } - const f32 DOT_THRESHOLD = 0.9995f; - if (dot > DOT_THRESHOLD) { - // If the inputs are too close for comfort, linearly interpolate - // and normalize the result. - out_quaternion = (quat){q0.x + ((q1.x - q0.x) * percentage), - q0.y + ((q1.y - q0.y) * percentage), - q0.z + ((q1.z - q0.z) * percentage), - q0.w + ((q1.w - q0.w) * percentage)}; + const f32 DOT_THRESHOLD = 0.9995f; + if (dot > DOT_THRESHOLD) { + // If the inputs are too close for comfort, linearly interpolate + // and normalize the result. + out_quaternion = + (quat){ q0.x + ((q1.x - q0.x) * percentage), q0.y + ((q1.y - q0.y) * percentage), + q0.z + ((q1.z - q0.z) * percentage), q0.w + ((q1.w - q0.w) * percentage) }; - return quat_normalise(out_quaternion); - } + return quat_normalise(out_quaternion); + } - // Since dot is in range [0, DOT_THRESHOLD], acos is safe - f32 theta_0 = cos(dot); // theta_0 = angle between input vectors - f32 theta = theta_0 * percentage; // theta = angle between v0 and result - f32 sin_theta = sin(theta); // compute this value only once - f32 sin_theta_0 = sin(theta_0); // compute this value only once + // Since dot is in range [0, DOT_THRESHOLD], acos is safe + f32 theta_0 = cos(dot); // theta_0 = angle between input vectors + f32 theta = theta_0 * percentage; // theta = angle between v0 and result + f32 sin_theta = sin(theta); // compute this value only once + f32 sin_theta_0 = sin(theta_0); // compute this value only once - f32 s0 = - cos(theta) - - dot * sin_theta / sin_theta_0; // == sin(theta_0 - theta) / sin(theta_0) - f32 s1 = sin_theta / sin_theta_0; + f32 s0 = cos(theta) - dot * sin_theta / sin_theta_0; // == sin(theta_0 - theta) / sin(theta_0) + f32 s1 = sin_theta / sin_theta_0; - return (quat){(q0.x * s0) + (q1.x * s1), (q0.y * s0) + (q1.y * s1), - (q0.z * s0) + (q1.z * s1), (q0.w * s0) + (q1.w * s1)}; + return (quat){ (q0.x * s0) + (q1.x * s1), (q0.y * s0) + (q1.y * s1), (q0.z * s0) + (q1.z * s1), + (q0.w * s0) + (q1.w * s1) }; } // --- Matrix Implementations |