Libgdx - 黑屏神秘

Question

我想在libGDX中使用Mesh类做一个简单的渐变.这应该是一个包含渐变的绘制矩形,但问题是矩形是完全黑色的!

我的代码:

public class HomeScreen extends
                        ScreenAdapter {

    OrthographicCamera  camera;
    Mesh                mesh;
    ShaderProgram       shader;

    public HomeScreen() {
        Logger.message("HomeScreen()", "^");
        this.camera = new OrthographicCamera(2, 2);
        this.mesh = new Mesh(false, 4, 4,
                                new VertexAttribute(Usage.Position, 3, ShaderProgram.POSITION_ATTRIBUTE),
                                new VertexAttribute(Usage.ColorPacked, 4, ShaderProgram.COLOR_ATTRIBUTE)
                );
        this.shader = SpriteBatch.createDefaultShader();

        this.camera.position.set(0, 0, 0);
        this.camera.update();
        this.mesh.setVertices(new float[] {
                -0.5f, -0.5f, 0, Color.BLUE.toFloatBits(),
                -0.5f, 0.5f, 0, Color.RED.toFloatBits(),
                0.5f, 0.5f, 0, Color.RED.toFloatBits(),
                0.5f, -0.5f, 0, Color.BLUE.toFloatBits(),
        });
        this.mesh.setIndices(new short[] {
                0, 1, 3, 2
        });
        Logger.message("HomeScreen()", "$");
    }

    @Override
    public void dispose() {
        Logger.message("HomeScreen.dipose()", "^");
        this.mesh.dispose();
        this.shader.dispose();
        Logger.message("HomeScreen.dipose()", "$");
    }

    @Override
    public void render(final float delta) {
        Gdx.gl.glClearColor(1, 1, 1, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        this.shader.begin();
        this.shader.setUniformMatrix("u_projTrans", this.camera.combined);
        this.mesh.render(this.shader, GL20.GL_TRIANGLE_STRIP);
        this.shader.end();
    }
}

结果 :

http://snag.gy/oduhL.jpg

任何的想法 ？

Answer 1

libgdx中SpriteBatches的默认着色器需要纹理才能工作.在查看着色器代码时,会看到最终结果是顶点颜色和纹理颜色的组合:

gl_FragColor = v_color * texture2D(u_texture, v_texCoords);

当不提供纹理时,顶点颜色将乘以[0,0,0,0],这将导致黑色输出.