LibGdx图片变为灰色,并提取边缘

1.shader
v

attribute vec4 a_position;
attribute vec4 a_color;
attribute vec2 a_texCoord0;
varying vec4 v_color;
uniform mat4 u_projTrans;
varying vec2 v_textCoords;

void main() {
    v_color = a_color;
    v_color.a = v_color.a * (255.0/254.0);
    v_textCoords = a_texCoord0;
    gl_Position = u_projTrans * a_position;
}

f

#ifdef GL_ES
precision mediump float;
#endif
varying vec4 v_color;
varying vec2 v_textCoords;
uniform sampler2D u_texture;

void main() {
     float offset = 0.005;
     float Gx = -1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(-1.0, -1.0))).r+
                1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(1.0, -1.0))).r+
                -2.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(-1.0, 0.0))).r+
                2.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(1.0, 0.0))).r+
                -1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(-1.0, 1.0))).r+
                1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(1.0, 1.0))).r;


     float Gy = -1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(-1.0, -1.0))).r+
                -2.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(0.0, -1.0))).r+
                -1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(1.0, -1.0))).r+
                1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(-1.0, 1.0))).r+
                2.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(0.0, 1.0))).r+
                1.0 * (v_color* texture2D(u_texture,v_textCoords + offset * vec2(1.0, 1.0))).r;

    float edgeMagnitude = length(vec2(Gx, Gy));
    if(edgeMagnitude>0.9){
        gl_FragColor = vec4(0.0,0,0,1.0f);
    }else{
        discard;
    }
}

2.使用

public class LightGroup extends Group {
    private ShaderProgram program;
    public LightGroup(){
        program = new ShaderProgram(
                Gdx.files.internal("flight/cir.vert"),
                Gdx.files.internal("flight/cir.glsl")
        );
        Image image = new Image(Asset.getAsset().getTexture("cirtest.png"));
        addActor(image);
    }

    @Override
    public void draw(Batch batch, float parentAlpha) {
        batch.flush();
        batch.setShader(program);
        super.draw(batch, parentAlpha);
        batch.flush();
        batch.setShader(null);
    }
}

3.原图

image.png

处理后:

image.png
4.保存到本地

        stage.addAction(Actions.delay(0.4f,Actions.run(()->{
            Gdx.app.postRunnable(()->{
                Pixmap pixmap = ScreenUtils.getFrameBufferPixmap(0,0,Gdx.graphics.getWidth(),Gdx.graphics.getHeight());
                try {
                    PixmapIO.writePNG(Gdx.files.local("screenshot.png"), pixmap);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
//                Image image = new Image(new Texture(pixmap));
//                addActor(image);
                run();
            });

        })));

注意:一定是 Gdx.app.postRunnable,不可以在Actions.run中直接执行.具体原因是二者执行时机不同