android - getHeight 的类型未定义

Question

我是 Android 的新手，我在使用这个 tutorial 时遇到了一些麻烦.我得到的错误是 getHeight/Width/requestRender 对于 HelloOpenGLES20Activity 的类型是未定义的。包含错误的代码部分需要在教程末尾添加。我搜索了大约一个小时，但处理 getHeight 的大部分错误都是关于它返回 0。

这是类 (HelloOpenGLES20Activity):

package com.example.HelloOpenGLES20;

import android.app.Activity;
import android.content.Context;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
import android.view.Display;
import android.view.MotionEvent;

public class HelloOpenGLES20Activity extends Activity {

private GLSurfaceView mGLView;
private final float TOUCH_SCALE_FACTOR = 180.0f / 320;    
private HelloOpenGLES20Renderer mRenderer;    
private float mPreviousX;    
private float mPreviousY;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Create a GLSurfaceView instance and set it
// as the ContentView for this Activity
mGLView = new HelloOpenGLES20SurfaceView(this);
setContentView(mGLView);
}

@Override 
public boolean onTouchEvent(MotionEvent e) {
// MotionEvent reports input details from the touch screen
// and other input controls. In this case, you are only
// interested in events where the touch position changed.

float x = e.getX();
float y = e.getY();

switch (e.getAction()) {
case MotionEvent.ACTION_MOVE:

float dx = x - mPreviousX;
float dy = y - mPreviousY;

// reverse direction of rotation above the mid-line
if (y > getHeight() / 2) {
dx = dx * -1 ;
}

// reverse direction of rotation to left of the mid-line
if (x < getWidth() / 2) {
dy = dy * -1 ;
}

mRenderer.mAngle += (dx + dy) * TOUCH_SCALE_FACTOR;
requestRender();
}

mPreviousX = x;
mPreviousY = y;
return true;
}

@Override
protected void onPause() {
super.onPause();
// The following call pauses the rendering thread.
// If your OpenGL application is memory intensive,
// you should consider de-allocating objects that
// consume significant memory here.
mGLView.onPause();
}

@Override
protected void onResume() {
super.onResume();
// The following call resumes a paused rendering thread.
// If you de-allocated graphic objects for onPause()
// this is a good place to re-allocate them.
mGLView.onResume();
}





class HelloOpenGLES20SurfaceView extends GLSurfaceView {

    private HelloOpenGLES20Renderer mRenderer;

    public HelloOpenGLES20SurfaceView(Context context){
        super(context);
        // Create an OpenGL ES 2.0 context.
        setEGLContextClientVersion(2);

        // set the mRenderer member
        mRenderer = new HelloOpenGLES20Renderer();
        setRenderer(mRenderer);

        // Render the view only when there is a change
        setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
        }

}
}

这是 HelloOpenGLES20Renderer 类:

package com.example.HelloOpenGLES20;

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.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;

public class HelloOpenGLES20Renderer implements GLSurfaceView.Renderer {

    public void onSurfaceCreated(GL10 unused, EGLConfig config) {

        // Set the background frame color
        GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);

        // initialize the triangle vertex array
        initShapes();
        int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
        int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);

        mProgram = GLES20.glCreateProgram(); // create empty OpenGL 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 program executables

        // get handle to the vertex shader's vPosition member
        maPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");

        }


public void onDrawFrame(GL10 unused) {

// Redraw background color
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
//Add program to OpenGL environment
GLES20.glUseProgram(mProgram);

//Prepare the triangle data
GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, 12, triangleVB);
GLES20.glEnableVertexAttribArray(maPositionHandle);

//Create a rotation for the triangle (Boring! Comment this out:)
//long time = SystemClock.uptimeMillis() % 4000L;
//float angle = 0.090f * ((int) time);

//Use the mAngle member as the rotation value
Matrix.setRotateM(mMMatrix, 0, mAngle, 0, 0, 1.0f);
Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0);

//Apply a ModelView Projection transformation
GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);
//Draw the triangle
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);
}

public void onSurfaceChanged(GL10 unused, int width, int height) {
GLES20.glViewport(0, 0, width, height);

float ratio = (float) width / height;

// this projection matrix is applied to object coodinates
// in the onDrawFrame() method
Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 3, 7);
muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
Matrix.setLookAtM(mVMatrix, 0, 0, 0, -3, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
} 

private FloatBuffer triangleVB;
private int mProgram;   
private int maPositionHandle;
private int muMVPMatrixHandle;
private float[] mMVPMatrix = new float[16];
private float[] mMMatrix = new float[16];
private float[] mVMatrix = new float[16];
private float[] mProjMatrix = new float[16];
public float mAngle;
private void initShapes(){

float triangleCoords[] = {
// X, Y, Z
-0.5f, -0.25f, 0,
0.5f, -0.25f, 0,
0.0f, 0.559016994f, 0
}; 

// initialize vertex Buffer for triangle 
ByteBuffer vbb = ByteBuffer.allocateDirect(
// (# of coordinate values * 4 bytes per float)
triangleCoords.length * 4); 
vbb.order(ByteOrder.nativeOrder());// use the device hardware's native byte order
triangleVB = vbb.asFloatBuffer(); // create a floating point buffer from the ByteBuffer
triangleVB.put(triangleCoords); // add the coordinates to the FloatBuffer
triangleVB.position(0); // set the buffer to read the first coordinate

}

private final String vertexShaderCode = 
//This matrix member variable provides a hook to manipulate
//the coordinates of the objects that use this vertex shader
"uniform mat4 uMVPMatrix; \n" +

"attribute vec4 vPosition; \n" +
"void main(){ \n" +

//the matrix must be included as a modifier of gl_Position
" gl_Position = uMVPMatrix * vPosition; \n" +

"} \n";

private final String fragmentShaderCode = 
"precision mediump float; \n" +
"void main(){ \n" +
" gl_FragColor = vec4 (0.63671875, 0.76953125, 0.22265625, 1.0); \n" +
"} \n";

private 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;
    }



}

提前致谢。

Answer 1

尝试使用以下代码获取屏幕的宽度:

WindowManager w = getWindowManager(); 
Display d = w.getDefaultDisplay(); 
int width = d.getWidth(); 
int height = d.getHeight();

再试一遍，ontouchevent 放错了

希望对您有所帮助