【Cocos2d-x 007】 关于CCpoint的一些算法或者说扩展

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/** Returns opposite of point.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpNeg(const CCPoint v) //计算关于原点的对称点

{

return ccp(-v.x, -v.y);

}

/** Calculates sum of two points.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpAdd(const CCPoint v1, const CCPoint v2)//计算两个向量的和

{

return ccp(v1.x + v2.x, v1.y + v2.y);

}

/** Calculates difference of two points.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpSub(const CCPoint v1, const CCPoint v2)// 计算两个向量的差

{

return ccp(v1.x - v2.x, v1.y - v2.y);

}

/** Returns point multiplied by given factor.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpMult(const CCPoint v, const CGFloat s)// 给定一个因子，算向量的倍数

{

return ccp(v.x*s, v.y*s);

}

/** Calculates midpoint between two points.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpMidpoint(const CCPoint v1, const CCPoint v2)// 计算两个点得中心点

{

return ccpMult(ccpAdd(v1, v2), 0.5f);

}

/** Calculates dot product of two points.

@return CGFloat

@since v0.7.2

*/

static inline CGFloat

ccpDot(const CCPoint v1, const CCPoint v2)// 计算两个向量的点乘积

{

return v1.x*v2.x + v1.y*v2.y;

}

/** Calculates cross product of two points.

@return CGFloat

@since v0.7.2

*/

static inline CGFloat

ccpCross(const CCPoint v1, const CCPoint v2)// 计算两个向量的叉乘积

{

return v1.x*v2.y - v1.y*v2.x;

}

/** Calculates perpendicular of v, rotated 90 degrees counter-clockwise -- cross(v, perp(v)) >= 0

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpPerp(const CCPoint v)// 向量逆时针旋转后的点坐标

{

return ccp(-v.y, v.x);

}

/** Calculates perpendicular of v, rotated 90 degrees clockwise -- cross(v, rperp(v)) <= 0

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpRPerp(const CCPoint v)// 向量顺时针旋转后的点坐标

{

return ccp(v.y, -v.x);

}

/** Calculates the projection of v1 over v2.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpProject(const CCPoint v1, const CCPoint v2)// 计算向量V1在向量V2上的投影点

{

return ccpMult(v2, ccpDot(v1, v2)/ccpDot(v2, v2));

}

/** Rotates two points.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpRotate(const CCPoint v1, const CCPoint v2)

{

return ccp(v1.x*v2.x - v1.y*v2.y, v1.x*v2.y + v1.y*v2.x);

}

/** Unrotates two points.

@return CCPoint

@since v0.7.2

*/

static inline CCPoint

ccpUnrotate(const CCPoint v1, const CCPoint v2)

{

return ccp(v1.x*v2.x + v1.y*v2.y, v1.y*v2.x - v1.x*v2.y);

}

/** Calculates the square length of a CCPoint (not calling sqrt() )

@return CGFloat

@since v0.7.2

*/

static inline CGFloat

ccpLengthSQ(const CCPoint v)// 计算一个向量长度的平方值

{

return ccpDot(v, v);

}

/** Calculates distance between point an origin

@return CGFloat

@since v0.7.2

*/

CGFloat ccpLength(const CCPoint v);// 计算点和原点的距离，但不知道函数体在哪里

/** Calculates the distance between two points

@return CGFloat

@since v0.7.2

*/

CGFloat ccpDistance(const CCPoint v1, const CCPoint v2);// 两点间距离

/** Returns point multiplied to a length of 1.

@return CCPoint

@since v0.7.2

*/

CCPoint ccpNormalize(const CCPoint v);

/** Converts radians to a normalized vector.

@return CCPoint

@since v0.7.2

*/

CCPoint ccpForAngle(const CGFloat a);

/** Converts a vector to radians.

@return CGFloat

@since v0.7.2

*/

CGFloat ccpToAngle(const CCPoint v);

/** Clamp a value between from and to.

@since v0.99.1

*/

float clampf(float value, float min_inclusive, float max_inclusive);

/** Clamp a point between from and to.

@since v0.99.1

*/

CCPoint ccpClamp(CCPoint p, CCPoint from, CCPoint to);

/** Quickly convert CGSize to a CCPoint

@since v0.99.1

*/

CCPoint ccpFromSize(CGSize s);

/** Run a math operation function on each point component

* absf, fllorf, ceilf, roundf

* any function that has the signature: float func(float);

* For example: let's try to take the floor of x,y

* ccpCompOp(p,floorf);

@since v0.99.1

*/

CCPoint ccpCompOp(CCPoint p, float (*opFunc)(float));

/** Linear Interpolation between two points a and b

@returns

alpha == 0 ? a

alpha == 1 ? b

otherwise a value between a..b

@since v0.99.1

*/

CCPoint ccpLerp(CCPoint a, CCPoint b, float alpha);

/** @returns if points have fuzzy equality which means equal with some degree of variance.

@since v0.99.1

*/

BOOL ccpFuzzyEqual(CCPoint a, CCPoint b, float variance);

/** Multiplies a nd b components, a.x*b.x, a.y*b.y

@returns a component-wise multiplication

@since v0.99.1

*/

CCPoint ccpCompMult(CCPoint a, CCPoint b);

/** @returns the signed angle in radians between two vector directions

@since v0.99.1

*/

float ccpAngleSigned(CCPoint a, CCPoint b);

/** @returns the angle in radians between two vector directions

@since v0.99.1

*/

float ccpAngle(CCPoint a, CCPoint b);

/** Rotates a point counter clockwise by the angle around a pivot

@param v is the point to rotate

@param pivot is the pivot, naturally

@param angle is the angle of rotation cw in radians

@returns the rotated point

@since v0.99.1

*/

CCPoint ccpRotateByAngle(CCPoint v, CCPoint pivot, float angle);

/** A general line-line intersection test

@param p1

is the startpoint for the first line P1 = (p1 - p2)

@param p2

is the endpoint for the first line P1 = (p1 - p2)

@param p3

is the startpoint for the second line P2 = (p3 - p4)

@param p4

is the endpoint for the second line P2 = (p3 - p4)

@param s

is the range for a hitpoint in P1 (pa = p1 + s*(p2 - p1))

@param t

is the range for a hitpoint in P3 (pa = p2 + t*(p4 - p3))

@return bool

indicating successful intersection of a line

note that to truly test intersection for segments we have to make

sure that s & t lie within [0..1] and for rays, make sure s & t > 0

the hit point is p3 + t * (p4 - p3);

the hit point also is p1 + s * (p2 - p1);

@since v0.99.1

*/

BOOL ccpLineIntersect(CCPoint p1, CCPoint p2,

CCPoint p3, CCPoint p4,

float *s, float *t);

/*

ccpSegmentIntersect returns YES if Segment A-B intersects with segment C-D

@since v1.0.0

*/

BOOL ccpSegmentIntersect(CCPoint A, CCPoint B, CCPoint C, CCPoint D);

/*

ccpIntersectPoint returns the intersection point of line A-B, C-D

@since v1.0.0

*/

CCPoint ccpIntersectPoint(CCPoint A, CCPoint B, CCPoint C, CCPoint D);