无纹理四边形未在 OpenGL ES 3.0 中呈现

Question

我最近使用 javax.swing 框架编写了一个简单的游戏，并希望将其作为 android 应用程序发布。我做了一些研究，发现大多数应用程序都使用 java 和 OpenGL ES。我有一些 OpenGL 经验，但正在熟悉 OpenGL ES。但是，每当我尝试渲染一个简单的四边形（使用 GLES30 顶点数组）时，我只会看到我的红色背景（我用 GL10.glClearColor() 指定了它）。我很可能遗漏了一些非常明显的东西，但我花了很多时间研究但没有找到切实的结果。

这是我的 MainActivity 代码：

public class MainActivity extends Activity {

    private Screen screen;
    private Sketcher s;

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

        screen = findViewById(R.id.surface_view);
        screen.setEGLContextClientVersion(3);

        s = new Sketcher(getAssets());

        screen.setRenderer(s);
        screen.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
    }

    @Override
    public void onPause() {
        super.onPause();
        screen.onPause();
    }

    @Override
    public void onResume() {
        super.onResume();
        screen.onResume();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        s.free();
    }
}

请记住，Screen class 仅复制 GLSurfaceView 的构造函数并生成 onPause() 和 onResume() 方法 public。

速写者class:

public class Sketcher implements GLSurfaceView.Renderer {

    private Player p;

    private Shader pShader;

    private AssetManager am;

    Sketcher(AssetManager am) {
        this.am = am;
    }

    @Override
    public void onSurfaceCreated(GL10 unused, EGLConfig config) {
        p = new Player();
        //pShader = new Shader(am, "playerVertexShader.txt", "playerFragmentShader.txt");
        //pShader.setUniforms();

        GLES10.glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    }

    @Override
    public void onDrawFrame(GL10 unused) {
        GLES10.glClear(GLES10.GL_COLOR_BUFFER_BIT);

        //pShader.activate();

        GLES30.glBindVertexArray(p.getVaoID());
        GLES20.glEnableVertexAttribArray(0);

        GLES20.glDrawElements(GLES20.GL_TRIANGLES, p.getVertexCount(), GLES20.GL_UNSIGNED_INT, 0);

        GLES20.glDisableVertexAttribArray(0);
        GLES30.glBindVertexArray(0);

        //pShader.deactivate();
    }

    @Override
    public void onSurfaceChanged(GL10 unused, int width, int height) {
        GLES10.glViewport(0, 0, width, height);
    }

    void free() {
        p.free();
        //pShader.free();
    }
}

玩家class:

public class Player {

    public static final float RADIUS = 0.5f;

    private static final float ACC = 0.02f;
    private static final float MAX_SPEED = 2.0f;

    private static final int PRECISION = 10;

    private float x, y;
    private float vx, vy;

    private int vaoID;
    private int vBufferID;
    private int iBufferID;

    public Player() {
        int[] vao = new int[1];
        int[] buffers = new int[2];

        GLES30.glGenVertexArrays(1, vao, 0);
        vaoID = vao[0];

        GLES30.glGenBuffers(2, buffers, 0);
        vBufferID = buffers[0];
        iBufferID = buffers[1];

        ByteBuffer vBuffer = ByteBuffer.allocateDirect(Float.BYTES * 8).order(ByteOrder.nativeOrder());
        vBuffer.putFloat(-RADIUS);
        vBuffer.putFloat(-RADIUS);
        vBuffer.putFloat( RADIUS);
        vBuffer.putFloat(-RADIUS);
        vBuffer.putFloat( RADIUS);
        vBuffer.putFloat( RADIUS);
        vBuffer.putFloat(-RADIUS);
        vBuffer.putFloat( RADIUS);
        vBuffer.flip();

        /*
        vBuffer.put(0.0f);
        vBuffer.put(0.0f);

        for (int i = 0; i < PRECISION; i++) {
            double angle = Math.PI / PRECISION * i;

            vBuffer.put((float)(Math.sin(angle) * RADIUS));
            vBuffer.put((float)(Math.cos(angle) * RADIUS));
        }
        */

        ByteBuffer iBuffer = ByteBuffer.allocateDirect(Integer.BYTES * 6).order(ByteOrder.nativeOrder());
        iBuffer.putInt(0);
        iBuffer.putInt(1);
        iBuffer.putInt(2);
        iBuffer.putInt(0);
        iBuffer.putInt(2);
        iBuffer.putInt(3);
        iBuffer.flip();
        /*
        for (int i = 1; i < PRECISION - 1; i++) {
            iBuffer.put(0);
            iBuffer.put(i + 1);
            iBuffer.put(i);
        }

        iBuffer.put(0);
        iBuffer.put(1);
        iBuffer.put(PRECISION - 1);
        */

        GLES30.glBindVertexArray(vaoID);

        GLES20.glBindBuffer(GLES30.GL_ARRAY_BUFFER, vBufferID);
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vBuffer.capacity(), vBuffer, GLES20.GL_STATIC_DRAW);
        GLES20.glVertexAttribPointer(0, 2, GLES20.GL_FLOAT, false, 0, 0);

        GLES20.glBindBuffer(GLES30.GL_ELEMENT_ARRAY_BUFFER, iBufferID);
        GLES20.glBufferData(GLES20.GL_ELEMENT_ARRAY_BUFFER, iBuffer.capacity(), iBuffer, GLES20.GL_STATIC_DRAW);

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
        GLES30.glBindVertexArray(0);
    }

    public float getX() {
        return x;
    }

    public float getY() {
        return y;
    }

    public int getVaoID() {
        return vaoID;
    }

    public int getVertexCount() {
        return 6;
    }

    public void free() {
        GLES30.glDeleteVertexArrays(1, new int[] {vaoID}, 0);
        GLES30.glDeleteBuffers(2, new int[] {vBufferID, iBufferID}, 0);
    }
}

我注释掉了很多与游戏更相关的代码，因为我必须进行简化，直到达到最低点（绘制一个简单的无纹理四边形）。

这是着色器代码：

#version 300 es

layout(location = 0) in vec2 vertex;

void main() {
    gl_Position = vec4(vertex, 0.0, 1.0);
}


#version 300 es

out vec4 fragment;

void main() {
    fragment = vec4(0.0, 0.0, 0.0, 1.0);
}

Answer 1

当您创建 Index buffers 时，您就创建了一个“字节”缓冲区。这意味着每个索引都存储在一个字节中：

ByteBuffer iBuffer = ByteBuffer.allocateDirect(Integer.BYTES*6).order(ByteOrder.nativeOrder());
       iBuffer.putInt(0);
       iBuffer.putInt(1);

GLES20.glBindBuffer(GLES30.GL_ELEMENT_ARRAY_BUFFER, iBufferID);
GLES20.glBufferData(GLES20.GL_ELEMENT_ARRAY_BUFFER, iBuffer.capacity(), iBuffer, GLES20.GL_STATIC_DRAW);

因此绘制网格时指定的索引类型必须是GL_UNSIGNED_BYTE(glDrawElements)

GLES20.glDrawElements(GLES20.GL_TRIANGLES, p.getVertexCount(), GLES20.GL_UNSIGNED_BYTE, 0);

而不是GL_UNSIGNED_INT：

~~GLES20.glDrawElements(GLES20.GL_TRIANGLES, p.getVertexCount(), GLES20.GL_UNSIGNED_INT, 0);~~

也可以，也可以使用IntBuffer对应元素类型GL_UNSIGNED_INT.
或者将 ShortBuffer 与 GL_UNSIGNED_SHORT.

结合使用

确实在片段着色器中缺少 Precision qualifiers，它们不是可选的 (OpenGL ES)。例如添加默认精度限定符：

precision medium float;

无纹理四边形未在 OpenGL ES 3.0 中呈现

Untextured Quad not rendering in OpenGL ES 3.0

java

android

opengl-es

glsles

opengl-es-3.0