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Rotation around pivot point is a specific case of more general rotation function

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This commit is contained in:
Constantine Tarasenkov 2015-02-03 19:50:53 +03:00
parent 2e60b35c8e
commit 60cbb26f9f
2 changed files with 22 additions and 18 deletions
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37
src/raymath.c
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@ -131,34 +131,37 @@ void VectorScale(Vector3 *v, float scale)
v->z *= scale; v->z *= scale;
} }
// Rotate vector by axis and angle around the pivot point // Rotate vector by axis and angle from the global center
void VectorRotate(Vector3 *v, Vector3 pivot, Vector3 axis, float angle) void VectorRotate(Vector3 *v, Vector3 axis, float angle)
{ {
VectorNormalize(&axis); VectorNormalize(&axis);
float tx = v->x - pivot.x;
float ty = v->y - pivot.y;
float tz = v->z - pivot.z;
float a = angle * (PI / 180.0f); float a = angle * (PI / 180.0f);
float sina = sin(a); float sina = sin(a);
float cosa = cos(a); float cosa = cos(a);
float cosb = 1.0f - cosa; float cosb = 1.0f - cosa;
float xrot = tx * (axis.x * axis.x * cosb + cosa) float xrot = v->x * (axis.x * axis.x * cosb + cosa)
+ ty * (axis.x * axis.y * cosb - axis.z * sina) + v->y * (axis.x * axis.y * cosb - axis.z * sina)
+ tz * (axis.x * axis.z * cosb + axis.y * sina); + v->z * (axis.x * axis.z * cosb + axis.y * sina);
float yrot = tx * (axis.y * axis.x * cosb + axis.z * sina) float yrot = v->x * (axis.y * axis.x * cosb + axis.z * sina)
+ ty * (axis.y * axis.y * cosb + cosa) + v->y * (axis.y * axis.y * cosb + cosa)
+ tz * (axis.y * axis.z * cosb - axis.x * sina); + v->z * (axis.y * axis.z * cosb - axis.x * sina);
float zrot = tx * (axis.z * axis.x * cosb - axis.y * sina) float zrot = v->x * (axis.z * axis.x * cosb - axis.y * sina)
+ ty * (axis.z * axis.y * cosb + axis.x * sina) + v->y * (axis.z * axis.y * cosb + axis.x * sina)
+ tz * (axis.z * axis.z * cosb + cosa); + v->z * (axis.z * axis.z * cosb + cosa);
v->x = xrot + pivot.x; *v = (Vector3){ xrot, yrot, zrot };
v->y = yrot + pivot.y; }
v->z = zrot + pivot.z;
// Rotate vector by axis and angle around the pivot point
void VectorRotateAround(Vector3 *v, Vector3 pivot, Vector3 axis, float angle)
{
*v = VectorSubtract(*v, pivot);
VectorRotate(v, axis, angle);
*v = VectorAdd(*v, pivot);
} }
// Negate provided vector (invert direction) // Negate provided vector (invert direction)

3
src/raymath.h
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@ -86,7 +86,8 @@ Vector3 VectorPerpendicular(Vector3 v); // Calculate one vector
float VectorDotProduct(Vector3 v1, Vector3 v2); // Calculate two vectors dot product float VectorDotProduct(Vector3 v1, Vector3 v2); // Calculate two vectors dot product
float VectorLength(const Vector3 v); // Calculate vector lenght float VectorLength(const Vector3 v); // Calculate vector lenght
void VectorScale(Vector3 *v, float scale); // Scale provided vector void VectorScale(Vector3 *v, float scale); // Scale provided vector
void VectorRotate(Vector3 *v, Vector3 pivot, Vector3 axis, float angle); // Rotate vector by axis and angle around the pivot point void VectorRotate(Vector3 *v, Vector3 axis, float angle); // Rotate vector by axis and angle from the global center
void VectorRotateAround(Vector3 *v, Vector3 pivot, Vector3 axis, float angle); // Rotate vector by axis and angle around the pivot point
void VectorNegate(Vector3 *v); // Negate provided vector (invert direction) void VectorNegate(Vector3 *v); // Negate provided vector (invert direction)
void VectorNormalize(Vector3 *v); // Normalize provided vector void VectorNormalize(Vector3 *v); // Normalize provided vector
float VectorDistance(Vector3 v1, Vector3 v2); // Calculate distance between two points float VectorDistance(Vector3 v1, Vector3 v2); // Calculate distance between two points