java - 如何在libgdx java中使用渐变颜色绘制曲线

Question

我想像这张图一样用渐变色画一条曲线

这是我的曲线绘制代码，但此代码仅适用于一种颜色。

public class Test extends ApplicationAdapter{

//create paths
private Bezier<Vector2> path1; 
private ShapeRenderer sr;

@Override
public void create () {

    // set up random control points
    int width = Gdx.graphics.getWidth();
    int height = Gdx.graphics.getHeight();
    int points = 4;
    Vector2[] controlPoints = new Vector2[points];
    for (int i = 0; i < points; i++) {
       int x = (int) (Math.random() * width) ;
       int y = (int) (Math.random() * height);
       Vector2 point = new Vector2(x, y);
       controlPoints[i] = point;
    }


    path1 = new Bezier<Vector2>(controlPoints);


    sr = new ShapeRenderer();
    sr.setAutoShapeType(true);
}




@Override
public void render () {
    Gdx.gl.glClearColor(0f, 0f, 0f, 0f);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

    sr.begin();
    sr.setColor(Color.WHITE);

    //draw path1
    for(int i = 0; i < 100; ++i){
        float t = i /100f;
        // create vectors to store start and end points of this section of the curve
        Vector2 st = new Vector2();
        Vector2 end = new Vector2();
        // get the start point of this curve section
        path1.valueAt(st,t);
        // get the next start point(this point's end)
        path1.valueAt(end, t-0.01f);
        // draw the curve
        sr.line(st.x, st.y, end.x, end.y);

    }



    sr.end();
}

@Override
public void dispose () {
}

我可以通过以下两种方法绘制一个矩形和一条使用渐变颜色的线

shapeRenderer.filledRect(x, y, width, height, lightBlue, lightBlue, darkBlue, darkBlue);

和

shapeRenderer.line(x, y, x2, y2, Color.RED, Color.GREEN);

但是我需要用渐变颜色绘制曲线，我搜索了很多，还没有找到任何解决方案。

所以请帮助我。

Answer 1

您可以使用开始颜色和结束颜色之间的线性插值找到每个部分的颜色。像这样:

Color color = new Color();

@Override
public void render() {
    Gdx.gl.glClearColor(0f, 0f, 0f, 0f);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

    sr.begin();

    Color startColor = Color.YELLOW;
    Color endColor = Color.RED;

    //draw path1
    for (int i = 0; i < 100; ++i) {
        float t = i / 100f;
        //interpolate linearly between start and end colors
        sr.setColor(color
                .set(startColor)
                .lerp(endColor, t)
        );
        // create vectors to store start and end points of this section of the curve
        Vector2 st = new Vector2();
        Vector2 end = new Vector2();
        // get the start point of this curve section
        path1.valueAt(st, t);
        // get the next start point(this point's end)
        path1.valueAt(end, t - 0.01f);
        // draw the curve
        sr.line(st.x, st.y, end.x, end.y);
    }

    sr.end();
}