Question

我正在尝试在我的应用中绘制透明纹理（文本）。奇怪的是，它适用于最新的Nexus 7和我的第二代Moto X，但在最初的Nexus 7上，纹理只是黑色。我已启用混合，纹理为512x512，因此它不是二次幂的问题。我也只是使用GL10，应该支持所有东西，对吗？纹理在这个设备上不起作用的任何原因？

gl.glEnable(GL10.GL_BLEND);
gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
gl.glEnable(GL10.GL_TEXTURE_2D);
// text drawn here
gl.glDisable(GL10.GL_TEXTURE_2D);
gl.glDisable(GL10.GL_BLEND);

这是纹理初始化，我加载纹理图集：

public void loadGlyphs(GL10 gl, Context context) {
    Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.text_bitmap);
    gl.glGenTextures(1, textures, 0);
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);

    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);

    GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);

    bitmap.recycle();
}

Top显示旧Nexus 7上发生的情况。底部图片是Moto X。

Bad

Good

编辑：这是一个完整的例子。没有透明度，不会在旧的Nexus 7上绘制任何东西。如果我摆脱了纹理的东西，它就像它应该的那样绘制白色的正方形。

MainActivity.java

import android.app.Activity;
import android.opengl.GLSurfaceView;
import android.os.Bundle;


public class MainActivity extends Activity {

    private GLSurfaceView glView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        glView = new TestView(this);
        setContentView(glView);
    }

    @Override
    protected void onPause() {
        super.onPause();
        glView.onPause();
    }

    @Override
    protected void onResume() {
        super.onResume();
        glView.onResume();
    }
}

TestView.java

import android.content.Context;
import android.opengl.GLSurfaceView;

public class TestView extends GLSurfaceView {
    private TestRenderer renderer;

    public TestView(Context context) {
        super(context);

        renderer = new TestRenderer(context);
        setRenderer(renderer);
    }
}

TestRenderer.java

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLSurfaceView;
import android.opengl.GLU;
import android.opengl.GLUtils;

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

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

public class TestRenderer implements GLSurfaceView.Renderer {

    private FloatBuffer floatBuffer;
    private FloatBuffer textureBuffer;
    private Context context;
    private int[] textures;

    public TestRenderer(Context context) {
        this.context = context;
        textures = new int[1];
    }

    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        floatBuffer = ByteBuffer.allocateDirect(4 * 2 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        floatBuffer.put(-0.5f);
        floatBuffer.put(-0.5f);
        floatBuffer.put(-0.5f);
        floatBuffer.put(0.5f);
        floatBuffer.put(0.5f);
        floatBuffer.put(-0.5f);
        floatBuffer.put(0.5f);
        floatBuffer.put(0.5f);
        floatBuffer.rewind();

        textureBuffer = ByteBuffer.allocateDirect(4*2*4).order(ByteOrder.nativeOrder()).asFloatBuffer();
        textureBuffer.put(0);
        textureBuffer.put(1);
        textureBuffer.put(0);
        textureBuffer.put(0);
        textureBuffer.put(1);
        textureBuffer.put(1);
        textureBuffer.put(1);
        textureBuffer.put(0);
        textureBuffer.rewind();

        Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.test);
        gl.glGenTextures(1, textures, 0);
        gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
        GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
        bitmap.recycle();
    }

    public void onSurfaceChanged(GL10 gl, int w, int h) {
        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        GLU.gluPerspective(gl, 45.0f, (float) w / (float) h, 0.1f, 100.0f);
        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();
    }

    public void onDrawFrame(GL10 gl) {
        gl.glLoadIdentity();
        gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
        gl.glTranslatef(0.0f, 0.0f, -5.0f);

        gl.glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

        gl.glEnable(GL10.GL_TEXTURE_2D);
        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
        gl.glFrontFace(GL10.GL_CW);
        gl.glVertexPointer(2, GL10.GL_FLOAT, 0, floatBuffer);
        gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);
        gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
        gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glDisable(GL10.GL_TEXTURE_2D);
    }
}

编辑：这是我在网上找到的一个例子。如果我禁用GL_TEXTURE_2D，我会得到一个白色方块。如果我启用GL_TEXTURE_2D，我什么也得不到。

MainActivity 公共类MainActivity扩展了Activity {

    private GLSurfaceView glSurfaceView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);

        glSurfaceView = new GLSurfaceView(this);

        glSurfaceView.setRenderer(new GlRenderer(this));
        setContentView(glSurfaceView);
    }

    @Override
    protected void onResume() {
        super.onResume();
        glSurfaceView.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
        glSurfaceView.onPause();
    }

}

GlRenderer

public class GlRenderer implements Renderer {

    private Square square;
    private Context context;

    public GlRenderer(Context context) {
        this.context = context;
        this.square = new Square();
    }

    @Override
    public void onDrawFrame(GL10 gl) {
        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
        gl.glLoadIdentity();
        gl.glTranslatef(0.0f, 0.0f, -5.0f);
        square.draw(gl);
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
        if(height == 0) {
            height = 1;
        }
        gl.glViewport(0, 0, width, height);
        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();

        GLU.gluPerspective(gl, 45.0f, (float)width / (float)height, 0.1f, 100.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        square.loadGLTexture(gl, this.context);

        gl.glEnable(GL10.GL_TEXTURE_2D);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
        gl.glClearDepthf(1.0f);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glDepthFunc(GL10.GL_LEQUAL);
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
    }
}

方

public class Square {

    private FloatBuffer vertexBuffer;
    private float vertices[] = {
            -1.0f, -1.0f,  0.0f,
            -1.0f,  1.0f,  0.0f,
            1.0f, -1.0f,  0.0f,
            1.0f,  1.0f,  0.0f
    };

    private FloatBuffer textureBuffer;
    private float texture[] = {
            0.0f, 1.0f,
            0.0f, 0.0f,
            1.0f, 1.0f,
            1.0f, 0.0f
    };

    private int[] textures = new int[1];

    public Square() {
        ByteBuffer byteBuffer = ByteBuffer.allocateDirect(vertices.length * 4);
        byteBuffer.order(ByteOrder.nativeOrder());
        vertexBuffer = byteBuffer.asFloatBuffer();
        vertexBuffer.put(vertices);
        vertexBuffer.position(0);
        byteBuffer = ByteBuffer.allocateDirect(texture.length * 4);
        byteBuffer.order(ByteOrder.nativeOrder());
        textureBuffer = byteBuffer.asFloatBuffer();
        textureBuffer.put(texture);
        textureBuffer.position(0);
    }

    public void loadGLTexture(GL10 gl, Context context) {
        Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),
                R.drawable.test);

        gl.glGenTextures(1, textures, 0);
        gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);

        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);

        GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);

        bitmap.recycle();
    }

    public void draw(GL10 gl) {
        gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
        gl.glFrontFace(GL10.GL_CW);
        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
        gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);
        gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, vertices.length / 3);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
    }
}

Answer 1

纹理使用的是哪种颜色格式？它是否与着色器所期望的颜色格式相匹配？

如果您的颜色格式是RGBA8888并且着色器需要RGB256，您可能会遇到这样的问题。（它会在错误的位置查找alpha通道信息）

Answer 2

经过多次故障排除后，我能够通过添加纹理包装来解决这两个设备（可能是所有设备）的问题：

gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);

我不确定为什么这对两台设备是必要的，但不是其他两台设备。

Android OpenGL透明纹理绘制黑色

2 个答案: