package com.brashmonkey.spriter;
import static com.brashmonkey.spriter.Calculator.*;
import static com.brashmonkey.spriter.Interpolator.*;
/**
* Represents a curve in a Spriter SCML file.
* An instance of this class is responsible for tweening given data.
* The most important method of this class is {@link #tween(float, float, float)}.
* Curves can be changed with sub curves {@link Curve#subCurve}.
* @author Trixt0r
*
*/
public class Curve {
/**
* Represents a curve type in a Spriter SCML file.
* @author Trixt0r
*
*/
public static enum Type {
Instant, Linear, Quadratic, Cubic, Quartic, Quintic, Bezier;
}
/**
* Returns a curve type based on the given curve name.
* @param name the name of the curve
* @return the curve type. {@link Type#Linear} is returned as a default type.
*/
public static Type getType(String name){
if(name.equals("instant")) return Type.Instant;
else if(name.equals("quadratic")) return Type.Quadratic;
else if(name.equals("cubic")) return Type.Cubic;
else if(name.equals("quartic")) return Type.Quartic;
else if(name.equals("quintic")) return Type.Quintic;
else if(name.equals("bezier")) return Type.Bezier;
else return Type.Linear;
}
private Type type;
/**
* The sub curve of this curve, which can be <code>null</code>.
*/
public Curve subCurve;
/**
* The constraints of a curve which will affect a curve of the types different from {@link Type#Linear} and {@link Type#Instant}.
*/
public final Constraints constraints = new Constraints(0, 0, 0, 0);
/**
* Creates a new linear curve.
*/
public Curve(){
this(Type.Linear);
}
/**
* Creates a new curve with the given type.
* @param type the curve type
*/
public Curve(Type type){
this(type, null);
}
/**
* Creates a new curve with the given type and sub cuve.
* @param type the curve type
* @param subCurve the sub curve. Can be <code>null</code>
*/
public Curve(Type type, Curve subCurve){
this.setType(type);
this.subCurve = subCurve;
}
/**
* Sets the type of this curve.
* @param type the curve type.
* @throws SpriterException if the type is <code>null</code>
*/
public void setType(Type type){
if(type == null) throw new SpriterException("The type of a curve cannot be null!");
this.type = type;
}
/**
* Returns the type of this curve.
* @return the curve type
*/
public Type getType(){
return this.type;
}
private float lastCubicSolution = 0f;
/**
* Returns a new value based on the given values.
* Tweens the weight with the set sub curve.
* @param a the start value
* @param b the end value
* @param t the weight which lies between 0.0 and 1.0
* @return tweened value
*/
public float tween(float a, float b, float t){
t = tweenSub(0f,1f,t);
switch(type){
case Instant: return a;
case Linear: return linear(a, b, t);
case Quadratic: return quadratic(a, linear(a, b, constraints.c1), b, t);
case Cubic: return cubic(a, linear(a, b, constraints.c1), linear(a, b, constraints.c2), b, t);
case Quartic: return quartic(a, linear(a, b, constraints.c1), linear(a, b, constraints.c2), linear(a, b, constraints.c3), b, t);
case Quintic: return quintic(a, linear(a, b, constraints.c1), linear(a, b, constraints.c2), linear(a, b, constraints.c3), linear(a, b, constraints.c4), b, t);
case Bezier: Float cubicSolution = solveCubic(3f*(constraints.c1-constraints.c3) + 1f, 3f*(constraints.c3-2f*constraints.c1), 3f*constraints.c1, -t);
if(cubicSolution == null) cubicSolution = lastCubicSolution;
else lastCubicSolution = cubicSolution;
return linear(a, b, bezier(cubicSolution, 0f, constraints.c2, constraints.c4, 1f));
default: return linear(a, b, t);
}
}
/**
* Interpolates the given two points with the given weight and saves the result in the target point.
* @param a the start point
* @param b the end point
* @param t the weight which lies between 0.0 and 1.0
* @param target the target point to save the result in
*/
public void tweenPoint(Point a, Point b, float t, Point target){
target.set(this.tween(a.x, b.x, t), this.tween(a.y, b.y, t));
}
private float tweenSub(float a, float b, float t){
if(this.subCurve != null) return subCurve.tween(a, b, t);
else return t;
}
/**
* Returns a tweened angle based on the given angles, weight and the spin.
* @param a the start angle
* @param b the end angle
* @param t the weight which lies between 0.0 and 1.0
* @param spin the spin, which is either 0, 1 or -1
* @return tweened angle
*/
public float tweenAngle(float a, float b, float t, int spin){
if(spin>0){
if(b-a < 0)
b+=360;
}
else if(spin < 0){
if(b-a > 0)
b-=360;
}
else return a;
return tween(a, b, t);
}
/**
*
*/
public float tweenAngle(float a, float b, float t){
t = tweenSub(0f,1f,t);
switch(type){
case Instant: return a;
case Linear: return linearAngle(a, b, t);
case Quadratic: return quadraticAngle(a, linearAngle(a, b, constraints.c1), b, t);
case Cubic: return cubicAngle(a, linearAngle(a, b, constraints.c1), linearAngle(a, b, constraints.c2), b, t);
case Quartic: return quarticAngle(a, linearAngle(a, b, constraints.c1), linearAngle(a, b, constraints.c2), linearAngle(a, b, constraints.c3), b, t);
case Quintic: return quinticAngle(a, linearAngle(a, b, constraints.c1), linearAngle(a, b, constraints.c2), linearAngle(a, b, constraints.c3), linearAngle(a, b, constraints.c4), b, t);
case Bezier: Float cubicSolution = solveCubic(3f*(constraints.c1-constraints.c3) + 1f, 3f*(constraints.c3-2f*constraints.c1), 3f*constraints.c1, -t);
if(cubicSolution == null) cubicSolution = lastCubicSolution;
else lastCubicSolution = cubicSolution;
return linearAngle(a, b, bezier(cubicSolution, 0f, constraints.c2, constraints.c4, 1f));
default: return linearAngle(a, b, t);
}
}
public String toString(){
return getClass().getSimpleName()+"|["+type+":"+constraints+", subCurve: "+subCurve+"]";
}
/**
* Represents constraints for a curve.
* Constraints are important for curves which have a order higher than 1.
* @author Trixt0r
*
*/
public static class Constraints{
public float c1, c2, c3, c4;
public Constraints(float c1, float c2, float c3, float c4){
this.set(c1, c2, c3, c4);
}
public void set(float c1, float c2, float c3, float c4){
this.c1 = c1;
this.c2 = c2;
this.c3 = c3;
this.c4 = c4;
}
public String toString(){
return getClass().getSimpleName()+"| [c1:"+c1+", c2:"+c2+", c3:"+c3+", c4:"+c4+"]";
}
}
}