来自 gluUnProject 的 IllegalArgumentException

Question

我收到此错误消息

08-30 19:20:17.774: ERROR/AndroidRuntime(4681): FATAL EXCEPTION: GLThread 9
08-30 19:20:17.774: ERROR/AndroidRuntime(4681): java.lang.IllegalArgumentException: length - offset < n
08-30 19:20:17.774: ERROR/AndroidRuntime(4681):     at android.opengl.Matrix.multiplyMV(Native Method)
08-30 19:20:17.774: ERROR/AndroidRuntime(4681):     at android.opengl.GLU.gluUnProject(GLU.java:237)
08-30 19:20:17.774: ERROR/AndroidRuntime(4681):     at android.app.ui.GLSurfaceRenderer.vector3(GLSurfaceRenderer.java:70)
08-30 19:20:17.774: ERROR/AndroidRuntime(4681):     at android.app.ui.GLSurfaceRenderer.onDrawFrame(GLSurfaceRenderer.java:103)
08-30 19:20:17.774: ERROR/AndroidRuntime(4681):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1332)
08-30 19:20:17.774: ERROR/AndroidRuntime(4681):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1116)

使用以下代码：

import android.opengl.GLU;
import android.opengl.GLSurfaceView.Renderer;
import android.util.*;


public class GLSurfaceRenderer implements Renderer{


public static float setx, sety;
private static float posx, posy, posz = 100;
private double speed;
private static float rotation;
private static float statrotation;
public static boolean isPressed;

private static FlatColoredSquare square;
private static FlatColoredSquare statSquare;
public final static String TAG = "input";






    public GLSurfaceRenderer () {

    square = new FlatColoredSquare();
    statSquare = new FlatColoredSquare();
    rotation = (float) Math.floor(Math.random()*361);
    speed = 0.1;




    }

    public void vector3 (GL11 gl){

        int[] viewport = new int[4];
        float[] modelview = new float[16];
        float[] projection = new float[16];
        float winx, winy, winz;
        float[] newcoords = new float[3];

        gl.glGetIntegerv(GL11.GL_VIEWPORT, viewport, 0);
        ((GL11) gl).glGetFloatv(GL11.GL_MODELVIEW_MATRIX, modelview, 0);
        ((GL11) gl).glGetFloatv(GL11.GL_PROJECTION_MATRIX, projection, 0);

        winx = (float)setx;
        winy = (float)viewport[3] - sety;
        winz = 0;

        GLU.gluUnProject(winx, winy, winz, modelview, 0, projection, 0,   viewport, 0, newcoords, 0);
        posx = (int)newcoords[1];
        posy = (int)newcoords[2];
        posz = (int)newcoords[3];



        Log.d(TAG, "vector3 Used");
    }


 @Override
public void onDrawFrame(GL10 gl) {
         gl.glClear(GL10.GL_COLOR_BUFFER_BIT |
            GL10.GL_DEPTH_BUFFER_BIT);
    gl.glLoadIdentity();
    gl.glScalef(100, 100, 0);
    gl.glPushMatrix();
    gl.glRotatef(rotation, 0, 0, 1);
    gl.glTranslatef((float) speed/10, 0, 0);    
    square.draw(gl);    
    gl.glPopMatrix();

    gl.glPushMatrix();
    gl.glTranslatef(posx, posy, posz);
    gl.glRotatef(statrotation,0,0,1);
    statSquare.draw(gl);
    gl.glPopMatrix();


    statrotation++;
    speed++;
    Log.d(TAG, "Frame Drawn");
    vector3((GL11) gl);

}   

@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
    gl.glViewport(0, 0, width, height);
    gl.glMatrixMode(GL10.GL_PROJECTION);
    gl.glLoadIdentity();
    GLU.gluOrtho2D(gl, -width, width, -height, height);
    gl.glMatrixMode(GL10.GL_MODELVIEW);
    gl.glLoadIdentity();


}




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

}






} 

请注意，我尝试在 Draw 方法中调用 vector3() 方法，该方法似乎有效，因为它读取的内容足以在实际方法中找出错误。错误是在这一行抛出的。

GLU.gluUnProject(winx, winy, winz, modelview, 0, projection, 0,   viewport, 0, newcoords, 0);

请注意，在抛出错误时，setx 和 sety 应等于 0，因为屏幕尚未被触摸。

该错误可能与我的 glSurfaceView 有关吗？

import android.content.Context;
import android.opengl.GLSurfaceView;
import android.util.*;
import android.view.MotionEvent;



public class Input extends GLSurfaceView {

public GLSurfaceRenderer glSurfaceRenderer;
public float setx, sety;
public final static String TAG = "input";


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


    glSurfaceRenderer = new GLSurfaceRenderer();
    setRenderer(glSurfaceRenderer);


}


@Override
public boolean onTouchEvent(MotionEvent event){
    if (event.getAction() == MotionEvent.ACTION_DOWN){
    setx = event.getX();
    sety = event.getY();


    Log.d(TAG, "isPressed triggered");
    }
    return true;
}

}

Answer 1

我简单地查看了这个函数的源代码，它似乎期望您的 newcoords 向量的大小为 4 而不是 3。它们是齐次坐标，因此您还必须除以 w获取您的实际坐标。

请注意，您的代码中还存在另一个错误，在调用 gluUnProject 后，您对 newcoords 的索引超出了范围。第一个元素是 newcoords[0]，而不是 newcoords[1]。

我认为如果你使用这样的东西，它会工作得更好（虽然我没有测试这个）：

float[] newcoords = new float[4]; // Note size 4!!
GLU.gluUnProject(...);
float x = newcoords[0] / newcoords[3];
float y = newcoords[1] / newcoords[3];
float z = newcoords[2] / newcoords[3];