Libgdx 实现技能冷却效果

先看效果，左边的技能cd。

原理是用多个多边形组成类圆形的Mesh，再用一个圆形黑色半透明的图片生成Texture，调用bind（）方法，最后渲染mesh。

texture.bind();

mesh.render(GL10.GL_TRIANGLE_FAN);

看代码：

public class ProgressTimer {

public static final int DIRECTION_CLOCKWISE = -1;

public static final int DIRECTION_COUNTERCLOCKWISE = 1;

private int MAX_VERTICE;

private int MIN_VERTICE;

private Texture texture;

private Mesh mesh;

private int iVertice;

private float r;

private float fCenterX;

private float fCenterY;

private int iDirection;

public ProgressTimer(AssetManager manager, float centerX, float centerY, float r, int maxVertice, int minVertice, String textureName, int direction) {

fCenterX = centerX;

fCenterY = centerY;

this.r = r;

MAX_VERTICE = maxVertice – minVertice;

MIN_VERTICE = minVertice;

texture = manager.get(textureName, Texture.class);

iDirection = direction;

}

public void draw(float progress) {

createMesh(progress);

texture.bind();

mesh.render(GL10.GL_TRIANGLE_FAN);

}

private  void createMesh(float progress) {

iVertice = (int) (MAX_VERTICE * progress) + MIN_VERTICE;

double fTotalAngle = progress * 2 * Math.PI;

double fPerAngle = fTotalAngle / (iVertice – 2);

if(mesh != null)

mesh.dispose();

mesh = new Mesh(true, iVertice * 3, iVertice,

new VertexAttribute(Usage.Position, 3, “point”),

new VertexAttribute(Usage.TextureCoordinates, 2, “texCoords”));

float[] vertices = new float[iVertice * 5];

short[] indexs = new short[iVertice];

vertices[0] = fCenterX;

vertices[1] = fCenterY;

vertices[2] = 0;

vertices[3] = 0.5f;

vertices[4] = 0.5f;

indexs[0] = 0;

for(int i = 1; i < iVertice; i ++){

float fAngle =  (float) (iDirection * fPerAngle * (i – 1));

indexs[i] = (short) i;

for(int j = 0; j < 5; j ++){

int iIndex = i * 5 + j;

switch(j)

{

case 0:

vertices[iIndex] = (float) (fCenterX + r * Math.cos(fAngle));

break;

case 1:

vertices[iIndex] = (float) (fCenterY + r * Math.sin(fAngle));

break;

case 2:

vertices[iIndex] = 0;

break;

case 3:

vertices[iIndex] = (float) ( (Math.cos(fAngle) + 1) / 2);

break;

case 4:

vertices[iIndex] = (float) ( ((- Math.sin(fAngle)) + 1) / 2);

break;

}

}

}

mesh.setVertices(vertices);

mesh.setIndices(indexs);

}

}

使用方法

ProgressTimer progress = new ProgressTimer(manager, centerX, centerY, r, 16, 3, textureName, ProgressTimer.DIRECTION_COUNTERCLOCKWISE);

progress.draw(fCurTime / iCD)；