Java 类com.badlogic.gdx.graphics.glutils.FloatFrameBuffer 实例源码

@Override
public void create () {
    fb = new FrameBuffer(Format.RGBA8888, 200, 100, false);
    ffb = new FloatFrameBuffer(200, 100, false);

    // @off
    String vertexShader = 
          "attribute vec4 a_position; "
        + "varying vec2 v_position; "
        + "void main(){ "
        + "    v_position = a_position.xy; "
        + "    gl_Position = vec4(a_position.x, a_position.y, 0.0, 1.0); "
        + "}";

    String fragmentShader = 
          "#ifdef GL_ES\n"
       + "precision mediump float;\n"
       + "#endif\n" + "uniform vec3 u_color;"
        + "uniform vec2 u_viewport; "
       + "void main(void){ "
        + "    vec2 uv = gl_FragCoord.xy/u_viewport; "
       + "    float res = mix(0.0, 0.0001, uv.x); " // <--- // regular (non-float) texture loses precision here, res == 0 for every fragment
        + "    gl_FragColor = vec4(u_color, res); "
       + "}";

    fbshader = new ShaderProgram(vertexShader, fragmentShader);

    vertexShader = 
          "attribute vec4 a_position; "
       + "attribute vec4 a_color; "
       + "attribute vec2 a_texCoords; "
        + "uniform mat4 u_worldView; "
       + "varying vec4 v_color; "
        + "varying vec2 v_texCoords; "
       + "void main() "
        + "{ "
       + "    v_color = a_color; "
        + "    v_texCoords = a_texCoords; "
        + "    gl_Position =  u_worldView * a_position; "
        + "}";

    fragmentShader =
          "#ifdef GL_ES\n"
       + "precision mediump float;\n"
        + "#endif\n"
       + "varying vec2 v_texCoords; "
        + "uniform sampler2D u_fbtex, u_ffbtex; "
        + "vec4 getValue(vec4 col) {"
        + "    if (col.a > 0.00005)"
        + "        return vec4(col.rgb, 1.0);"
        + "    else"
        + "        return vec4(0.0, 0.0, 0.0, 1.0);"
        + "}"
        + "void main() "
        + "{ "
        + "    if (v_texCoords.y < 0.45)"
        + "        gl_FragColor = getValue(texture2D(u_fbtex, v_texCoords)); "
        + "    else if (v_texCoords.y > 0.55)"
        + "        gl_FragColor = getValue(texture2D(u_ffbtex, v_texCoords)); "
        + "}";
    // @on

    shader = new ShaderProgram(vertexShader, fragmentShader);
    createQuad();

    screenCamera = new OrthographicCamera(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    createScreenQuad();
}