mathtool.java

一个J2ME的3D 一个J2ME的3D 一个J2ME的3D

/**
 * 
 */
package Math;

/**
 * @author PanXu
 *
 */
public class MathTool {
	public MathTool() {
		super();
		// TODO 自动生成构造函数存根
	}
	//色彩掩码
	public static int R_MASK = 0x00ff0000;
	public static int G_MASK = 0x0000ff00;
	public static int B_MASK = 0x000000ff;
	
	// 查表
	public static float Sin [] = new float [361];
	public static float Cos [] = new float [361];
	
	
	
	/**
	 * 初始化三角函数表
	 *
	 */
	public static void InitSCos ()
	{
		float theta;
		for (int i = 0 ; i <= 360 ; i ++)
		{
			theta = ((float)i*PI/180.0f);
			Sin [i] = (float) Math.sin(theta);
			Cos [i] = (float) Math.cos(theta);
		}//for 
	}
	/*
	 * 数学常量
	 */
	public static float PI = 3.141592654f;
	
    //极小的浮点数
	public static float EPSILON_E3 = (float)(1E-3); 
	public static float EPSILON_E4 = (float)(1E-4);
	public static float EPSILON_E5 = (float)(1E-5);
	public static float EPSILON_E6 = (float)(1E-6);
	
	/*
	 * 数学函数
	 */
	/**
	 * 正切
	 */
	public static float Tan (int ang)
	{
		return (Sin [ang] / Cos [ang]);
	}
	
	/**
	 * 
	 * @param x 
	 * @return 平方根的倒数
	 */
	public static float InvSqrt (float x)
	{
		float xhalf = 0.5f*x;
		int i = Float .floatToIntBits(x);
		//int i = *(int*)&x;
		i = 0x5f3759df - (i >> 1); // 计算第一个近似根
		x = Float .intBitsToFloat(i);
		//x = *(float*)&i;
		x = x*(1.5f - xhalf*x*x); // 牛顿迭代法
		return x;
	}
	
	public static int abs (int i)
	{
		return i |= 0x8000000;
	}
}