主要是实现了手指在屏幕上滑动实现平移，两个手指进行缩放。主要是这部分矩阵还挺麻烦的。

效果图如下所示：

核心部分代码如下

触控事件处理：

@SuppressLint("ClickableViewAccessibility")

@Override

public boolean onTouch(View view, MotionEvent motionEvent) {

//ACTION_DOWN不return true，就无触发后面的各个事件

if (motionEvent != null) {

final float normalizedX =toOpenGLCoord(view,motionEvent.getX(),true);

final float normalizedY =toOpenGLCoord(view,motionEvent.getY(),false);

switch (motionEvent.getActionMasked()){

case MotionEvent.ACTION_DOWN:

X=normalizedX;

Y=normalizedY;

break;

case MotionEvent.ACTION_POINTER_DOWN:

isZooming=true;

float x1=toOpenGLCoord(view,motionEvent.getX(1),true);

float y1=toOpenGLCoord(view,motionEvent.getY(1),false);

dis_start=computeDis(normalizedX,x1,normalizedY,y1);

break;

case MotionEvent.ACTION_MOVE:

if(isZooming){

float x2=toOpenGLCoord(view,motionEvent.getX(1),true);

float y2=toOpenGLCoord(view,motionEvent.getY(1),false);

double dis=computeDis(normalizedX,x2,normalizedY,y2);

double scale=dis/dis_start;

zoom((float) scale);

dis_start=dis;

}else {

move(normalizedX - X, normalizedY - Y);

X = normalizedX;

Y = normalizedY;

}

break;

case MotionEvent.ACTION_POINTER_UP:

isZooming=false;

X = normalizedX;

Y = normalizedY;

break;

case MotionEvent.ACTION_UP:

break;

default:break;

}

return true;

}

return false;

}

/**

* 屏幕坐标系点转OpenGL坐标系

* @return

*/

private static float toOpenGLCoord(View view,float value,boolean isWidth){

if(isWidth){

return (value / (float) view.getWidth()) * 2 - 1;

}else {

return -((value / (float) view.getHeight()) * 2 - 1);

}

}

/**

* 计算两个点之间的距离

* @param x1

* @param x2

* @param y1

* @param y2

* @return

*/

private static double computeDis(float x1,float x2,float y1,float y2){

return sqrt(pow((x2-x1),2)+pow((y2-y1),2));

}

render部分矩阵处理：

private final float[] translateMatrix = new float[16];//平移矩阵

private final float[] zoomMatrix = new float[16];//缩放矩阵

@Override

public void onSurfaceCreated(GL10 gl10, EGLConfig eglConfig) {

glClearColor(1.0f, 1.0f, 1.0f, 1.0f);

//初始化平移矩阵和缩放矩阵为单位矩阵

setIdentityM(translateMatrix,0);//建立单位矩阵

setIdentityM(zoomMatrix,0);//建立单位矩阵

}

@Override

public void onDrawFrame(GL10 gl10) {

glClear(GL_COLOR_BUFFER_BIT);

//平移支持

//两个矩阵相乘

float[] temp = new float[16];

multiplyMM(temp, 0, projectionMatrix, 0, translateMatrix, 0);

float[] temp2 = new float[16];

multiplyMM(temp2, 0, zoomMatrix, 0, temp, 0);

Log.e(TAG,"重新绘制");

for(int i=0;i

Brush brush=brushes.get(i);

brush.draw(temp2);

}

}

/**

* 改变绘图坐标系的偏移值

* @param dx

* @param dy

*/

public void move(float dx, float dy){

//根据当前缩放的比例调节平移参数

translateM(translateMatrix,0,dx/zoomMatrix[0],dy/zoomMatrix[0],0);//添加平移参数

}

/**

* 缩放视图

* @param scale 缩放比例

*/

public void zoom(float scale){

scaleM(zoomMatrix,0,scale,scale,0);//添加缩放参数

}