One of the simple and practical algorithms of RPG based on COCOS2DX-the movement of characters

Recently wrote the RPG, found in the role of the movement of the object can still be a lot of mathematics before the knowledge (manager of all kinds of tangled brain repair), long time no blog, hot summed up the algorithm ideas, lest oneself after two days and forget.

known role speed and destination, for each frame position

We already know a character. Bodya speed to pixels per second

Float speed = 5

Destination is point destination

Current location is point currentposition = Bodya.getposition ()

So how do you calculate the current position of the character in the frame loop?

Scenario 1. Low computational weight, but not precise

VEC2 VEC = destination-currentposition;

Vec.normalize (); Unit of

Point nextposition = VEC * speed + currentposition

Scenario 2: The motion rotation function rotatebyangle Accurate, the computation quantity is big

Parameter 1. Role Current Location

Parameter 2. Speed vector

Parameter 3. Speed

Return: starting at point StartPoint, move the point of a range of pixels along a vector direction

Inline point getpointalongdirection (Point StartPoint, Vec2 dir, float range)
{
float radians = vec.getangle (VEC2 (0,1)); Clockwise is positive, counter-clockwise negativePoint Zerodegreepos = startPoint;Zerodegreepos.y = startpoint.y + range;Point Des2 = Zerodegreepos.rotatebyangle (StartPoint,-radians),//negative clockwise rotation
}

Scenario 3. On the idea of scenario 2, optimize the algorithm by vector formula

Use the vector collinear formula and the vector formula to push to:

the geometric representation of a vector collinear:

Set, wherein, when and only then, the vector collinear.

(1) if, then;
(2) if, then.

Parameter 1. Role Current Location

Parameter 2. Speed vector

Parameter 3. Speed

return: starting at point StartPoint, move the point of a range of pixels along a vector directionInline Point getpointalongdirection (Point StartPoint, Vec2 dir, float range){assert (range > 0);dir.normalize ();float x1 = dir.x;float y1 = dir.y;
float factor = sqrt (1/(x1 * x1 + y1 * y1)) * range;float x2 = factor * x1;float y2 = factor * y1;
Point des = startPoint; des . x + = x2; des . y + = y2;
return des;}

Original address

http://write.blog.csdn.net/postedit/47190919

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One of the simple and practical algorithms of RPG based on COCOS2DX-the movement of characters