自己动手实现OpenGL之glViewPort（一）

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直接上代码。

	public static   void glViewport(
            int x,
            int y,
            int width,
            int height
     ) 
	{
		int surfaceHeight = mInfo.height;
		float far = mViewPortZFar;
		float near = mViewPortZNear;
		float sx = width/2.0f;
		float ox = sx + x;
		float sy = height/2.0f;
		float oy = sy + surfaceHeight - height - y;   
		float A = (far - near)/2.0f;
		float B = (far + near)/2.0f;
		// compute viewport matrix
		float[][] f = new float[4][4];
	    f[0][0] = sx;  f[0][1] = 0;   f[0][2] = 0;  f[0][3] = ox;
		f[1][0] = 0;   f[1][1] =-sy;  f[1][2] = 0;  f[1][3] = oy;
		f[2][0] = 0;   f[2][1] = 0;   f[2][2] = A;  f[2][3] = B;
		f[3][0] = 0;   f[3][1] = 0;   f[3][2] = 0;  f[3][3] = 1;
		mCurrentViewPortMatrix = new M4();
		mCurrentViewPortMatrix.m = f;
	}

 

 

  

 public static void glDepthRangef(
        float zNear,
        float zFar
    ){
     mViewPortZNear = zNear;
     mViewPortZFar = zFar;
    }