在openGL android中旋转三角形

时间:2014-02-15 19:25:13

标签: java android opengl-es

我根据developer.android.com上的入门示例做了一个简单的应用程序。它工作正常,但我改变了旋转逻辑,现在它没有显示三角形。我不确定我是否理解矩阵的东西,所以如果有人能检查我的代码我想。 这是我认为可能有问题的SurfaceView方法:

@Override
public boolean onTouchEvent(MotionEvent e){
    float x = e.getX();
    float y = e.getY();

    switch(e.getAction()){
    case MotionEvent.ACTION_MOVE:
        float rotateX = 0.0f;
        float rotateY = 0.0f;
        float rotateZ = 0.0f;

        //na coluna da esquerda, rotação no eixo Z
        if(x < getWidth() / 3){
            rotateZ = (y - previousY);
        }
        //na coluna do meio, rotação no eixo X
        if(getWidth()/3 < x && x < 2*getWidth()/3){
            rotateX = (y - previousY);
        }
        //na coluna da direita, rotação no eixo Z invertido
        if(x > getWidth() / 3){
            rotateZ = - (y - previousY);
        }

        //na linha superior, rotação no eixo Z
        if(y < getHeight() / 3){
            rotateZ = (x - previousX);
        }
        //na linha do meio, rotação no eixo Y
        if(getHeight()/3 < y && y < 2*getHeight()/3){
            rotateY = (x - previousY);
        }
        //na linha inferior, rotação no eixo Z invertido
        if(y > 2*getHeight() / 3){
            rotateZ = - (x - previousX);
        }

        mRenderer.setAngulo(mRenderer.getAnguloX() + (rotateX) * TOUCH_SCALE_FACTOR,
                            mRenderer.getAnguloY() + (rotateY) * TOUCH_SCALE_FACTOR,
                            mRenderer.getAnguloZ() + (rotateZ) * TOUCH_SCALE_FACTOR);
        requestRender();

    }
    previousX = x;
    previousY = y;
    return true;
}

这是渲染器方法:

@Override
public void onDrawFrame(GL10 unused) {

    //desenha o fundo
    GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

    //define a posição da camera
    //Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, lookX, lookY, lookZ, upX, upY, upZ);
    Matrix.setLookAtM(mViewMatrix, 0, 0, 0, -5f, 0f, 0f, 0f, 0f, 1.0f, 0.0f);

    //cria uma matrix para a rotação de cada angulo
    Matrix.setRotateM(xRotationMatrix, 0, anguloX, 1, 0, 0);
    Matrix.setRotateM(yRotationMatrix, 0, anguloY, 0, 1, 0);
    Matrix.setRotateM(zRotationMatrix, 0, anguloZ, 0, 0, 1);

    float[] mMatrix = new float[16];
    //aplica todas as rotações na matrix scratch
    Matrix.multiplyMM(mMatrix, 0, xRotationMatrix, 0, mMatrix, 0);
    Matrix.multiplyMM(mMatrix, 0, yRotationMatrix, 0, mMatrix, 0);
    Matrix.multiplyMM(mMatrix, 0, zRotationMatrix, 0, mMatrix, 0);

    // Calcula a view e depois a projeção
    Matrix.multiplyMM(resultingMatrix, 0, mViewMatrix, 0, mMatrix, 0);
    Matrix.multiplyMM(resultingMatrix, 0, mProjectionMatrix, 0, resultingMatrix, 0);

    // Draw shape
    triangulo.draw(resultingMatrix);
}

Triangulo类必须是正确的,因为自上次应用程序运行以来我没有更改它。

1 个答案:

答案 0 :(得分:0)

嗯,我彻底分析了你的代码,似乎没有任何问题。

但是,我想问题是这样的:

致电时

Matrix.setLookAtM(mViewMatrix, 0, 0, 0, -5f, 0f, 0f, 0f, 0f, 1.0f, 0.0f);

您正在将相机设置为Z = -5并朝向原点,即朝向+ ve Z方向。

(我猜最初三角形的顶点必须在XY平面内,因此三角形是可见的。)

然后当你打电话

Matrix.setRotateM(zRotationMatrix, 0, anguloZ, 0, 0, 1);

它围绕Z轴旋转三角形,这很好。

但是你打电话

Matrix.setRotateM(xRotationMatrix, 0, anguloX, 1, 0, 0);
Matrix.setRotateM(yRotationMatrix, 0, anguloY, 0, 1, 0);

这里是围绕X和Y轴旋转三角形,因为三角形没有厚度, 它变得不可见。

可能的修复:

1)移除绕X和Y轴的旋转并检查它是否有效。

                  OR

2)放一个立方体而不是三角形,看它是否有效。

                  OR

3)如果两者都不起作用,请给我完整的代码。我将调试并运行它。

最好的运气