我正在跟随 developer.android.com 上有关使用 opengl 的教程进行编码，但是我遇到了一些错误，我试图修复它们，但并没有成功。我已经创建了一个主活动，在该活动中，当您按下按钮时，意图会打开一个显示黑屏但无法显示三角形的 opengl 活动。你能告诉我问题出在哪里吗？
这是我的 MainActivity 类：
那是我的渲染器类：
这是我的 MainActivity 类：
package com.eBook.test;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button button = (Button)findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v){
Intent intent = new Intent (MainActivity.this, OpenGLES20Activity.class);
startActivity(intent);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
这个看起来没问题，现在这是我的OpenGL活动类：
package com.eBook.test;
import android.app.Activity;
import android.content.Context;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
public class OpenGLES20Activity extends Activity {
private GLSurfaceView mGLView;
class MyGLSurfaceView extends GLSurfaceView {
public MyGLSurfaceView(Context context){
super(context);
// Create an OpenGL ES 2.0 context
setEGLContextClientVersion(2);
// Set the Renderer for drawing on the GLSurfaceView
setRenderer(new MyRenderer());
setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Create a GLSurfaceView instance and set it
// as the ContentView for this Activity.
mGLView = new MyGLSurfaceView(this);
setContentView(mGLView);
}
@Override
protected void onPause() {
mGLView.onPause();
super.onPause();
}
@Override
protected void onResume() {
mGLView.onResume();
super.onResume();
}
}
那是我的渲染器类：
package com.eBook.test;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
public class MyRenderer implements GLSurfaceView.Renderer {
private Triangle mTriangle;
public void onSurfaceCreated(GL10 unused, EGLConfig config) {
// Set the background frame color
GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
// initialize a triangle
mTriangle = new Triangle();
}
public void onDrawFrame(GL10 unused) {
// Redraw background color
mTriangle.draw();
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
}
public void onSurfaceChanged(GL10 unused, int width, int height) {
GLES20.glViewport(0, 0, width, height);
}
public static int loadShader(int type, String shaderCode){
// create a vertex shader type (GLES20.GL_VERTEX_SHADER)
// or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
int shader = GLES20.glCreateShader(type);
// add the source code to the shader and compile it
GLES20.glShaderSource(shader, shaderCode);
GLES20.glCompileShader(shader);
return shader;
}
}
还有三角形类：
package com.eBook.test;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import android.opengl.GLES20;
public class Triangle {
private FloatBuffer vertexBuffer;
private int mProgram;
private int mPositionHandle;
private int mColorHandle;
// number of coordinates per vertex in this array
static final int COORDS_PER_VERTEX = 3;
static float triangleCoords[] = { // in counterclockwise order:
0.0f, 0.622008459f, 0.0f, // top
-0.5f, -0.311004243f, 0.0f, // bottom left
0.5f, -0.311004243f, 0.0f // bottom right
};
// Set color with red, green, blue and alpha (opacity) values
float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 1.0f };
private final String vertexShaderCode =
"attribute vec4 vPosition;" +
"void main() {" +
" gl_Position = vPosition;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"uniform vec4 vColor;" +
"void main() {" +
" gl_FragColor = vColor;" +
"}";
public Triangle() {
int vertexShader = MyRenderer.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
int fragmentShader = MyRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
mProgram = GLES20.glCreateProgram(); // create empty OpenGL ES Program
GLES20.glAttachShader(mProgram, vertexShader); // add the vertex shader to program
GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
GLES20.glLinkProgram(mProgram); // creates OpenGL ES program executables
// initialize vertex byte buffer for shape coordinates
ByteBuffer bb = ByteBuffer.allocateDirect(
// (number of coordinate values * 4 bytes per float)
triangleCoords.length * 4);
// use the device hardware's native byte order
bb.order(ByteOrder.nativeOrder());
// create a floating point buffer from the ByteBuffer
vertexBuffer = bb.asFloatBuffer();
// add the coordinates to the FloatBuffer
vertexBuffer.put(triangleCoords);
// set the buffer to read the first coordinate
vertexBuffer.position(0);
}
public void draw() {
// Add program to OpenGL ES environment
GLES20.glUseProgram(mProgram);
// get handle to vertex shader's vPosition member
mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
// Enable a handle to the triangle vertices
GLES20.glEnableVertexAttribArray(mPositionHandle);
// Prepare the triangle coordinate data
int vertexStride = 3;
GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,
GLES20.GL_FLOAT, false,
vertexStride, vertexBuffer);
// get handle to fragment shader's vColor member
mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");
// Set color for drawing the triangle
GLES20.glUniform4fv(mColorHandle, 1, color, 0);
// Draw the triangle
int vertexCount = 6;
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);
// Disable vertex array
GLES20.glDisableVertexAttribArray(mPositionHandle);
}
}
我不太清楚vertexCount和vertexStride应该取何值，从逻辑上讲，vertexCount可能应该是3，但vertexStride我不确定。