android - 为什么这个 Android 镜面照明示例没有按预期工作？

Question

为什么以下代码生成的二进制文件中没有出现镜面高光？

package com.example.helloandroid;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.opengl.GLSurfaceView.Renderer;

public class TestRenderer implements Renderer {
    private FloatBuffer vb;
    private FloatBuffer mab, mdb, msb;

    private FloatBuffer lPos;
    private FloatBuffer lab, ldb, lsb;

    public TestRenderer() {
        vb = ByteBuffer.allocateDirect(24 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        vb.put(new float[]{
            110.0f, 240.0f,
            110.0f, 190.0f,
            160.0f, 240.0f,
            160.0f, 190.0f,
            210.0f, 240.0f,
            210.0f, 190.0f,
            110.0f, 290.0f,
            110.0f, 240.0f,
            160.0f, 290.0f,
            160.0f, 240.0f,
            210.0f, 290.0f,
            210.0f, 240.0f});
        vb.position(0);
        mab = ByteBuffer.allocateDirect(4 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        mab.put(new float[]{1.0f, 0.0f, 0.0f, 1.0f});
        mab.position(0);
        mdb = ByteBuffer.allocateDirect(4 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        mdb.put(new float[]{0.0f, 1.0f, 0.0f, 1.0f});
        mdb.position(0);
        msb = ByteBuffer.allocateDirect(4 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        msb.put(new float[]{0.0f, 0.0f, 1.0f, 1.0f});
        msb.position(0);

        lPos = ByteBuffer.allocateDirect(4 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        lPos.put(new float[]{160.0f, 240.0f, 10.0f, 1.0f});
        lPos.position(0);
        lab = ByteBuffer.allocateDirect(4 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        // THIS WORKS..
        lab.put(new float[]{0.0f, 0.0f, 0.0f, 1.0f});
        lab.position(0);
        ldb = ByteBuffer.allocateDirect(4 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        // SO DOES THIS..
        ldb.put(new float[]{0.0f, 0.0f, 0.0f, 1.0f});
        ldb.position(0);
        // BUT NOT THIS
        lsb = ByteBuffer.allocateDirect(4 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        lsb.put(new float[]{1.0f, 1.0f, 1.0f, 1.0f});
        lsb.position(0);
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

        gl.glEnable(GL10.GL_LIGHTING);
        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

        gl.glMaterialfv(GL10.GL_FRONT, GL10.GL_AMBIENT, mab);
        gl.glMaterialfv(GL10.GL_FRONT, GL10.GL_DIFFUSE, mdb);
        gl.glMaterialfv(GL10.GL_FRONT, GL10.GL_SPECULAR, msb);

        gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_POSITION, lPos);
        gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_AMBIENT, lab);
        gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_DIFFUSE, ldb);
        gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_SPECULAR, lsb);
        gl.glEnable(GL10.GL_LIGHT0);
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
        gl.glViewport(0, 0, width, height);

        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        gl.glOrthof(0.0f, width, 0.0f, height, -1.0f, 1.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();
        gl.glTranslatef(0.0f, 0.0f, -1.0f);
    }

    @Override
    public void onDrawFrame(GL10 gl) {
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

        gl.glVertexPointer(2, GL10.GL_FLOAT, 0, vb);
        gl.glNormal3f(0.0f, 0.0f, 1.0f);
        gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 6);
        gl.glDrawArrays(GL10.GL_LINE_STRIP, 6, 6);
    }
}

这是我从代码中看到的原样(只有镜面照明组件):http://i.imgur.com/4kvIx.png

只有一个环境照明组件:http://i.imgur.com/80Tjx.png

只有一个漫射照明组件:http://i.imgur.com/r5PkO.png

可能有趣的是，我对 glOrtho 的调用中的 zNear/zFar 参数似乎没有剪切任何内容。我是否正确设置了场景以查看镜面反射高光(我确实尝试将光定位在顶点附近)？

Answer 1

OpenGL ES 只接受 GL_FRONT_AND_BACK。在这里查看 glMaterial

http://www.khronos.org/opengles/sdk/1.1/docs/man/glMaterial.xml