Unity下GL没有画圆的函数，只能自己来了。
如果能帮到大家，我也很高兴。
虽然没有画圆的函数，但是能画直线，利用这一点，配合微积分什么的，就可以画出来了。反正就是花很多连在一起的直线，每条直线足够短的时候，就足够圆了
1 void DrawCircle(float x, float y, float z, float r, float accuracy) 2 { 3 GL.PushMatrix (); 4 //绘制2D图像 5 GL.LoadOrtho (); 6 7 float stride = r * accuracy; 8 float size = 1 / accuracy; 9 float x1 = x, x2 = x, y1 = 0, y2 = 0; 10 float x3 = x, x4 = x, y3 = 0, y4 = 0; 11 12 double squareDe; 13 squareDe = r * r - Math.Pow (x - x1, 2); 14 squareDe = squareDe > 0 ? squareDe : 0; 15 y1 = (float)(y + Math.Sqrt (squareDe)); 16 squareDe = r * r - Math.Pow (x - x1, 2); 17 squareDe = squareDe > 0 ? squareDe : 0; 18 y2 = (float)(y - Math.Sqrt (squareDe)); 19 for (int i = 0; i < size; i++) { 20 x3 = x1 + stride; 21 x4 = x2 - stride; 22 squareDe = r * r - Math.Pow (x - x3, 2); 23 squareDe = squareDe > 0 ? squareDe : 0; 24 y3 = (float)(y + Math.Sqrt (squareDe)); 25 squareDe = r * r - Math.Pow (x - x4, 2); 26 squareDe = squareDe > 0 ? squareDe : 0; 27 y4 = (float)(y - Math.Sqrt (squareDe)); 28 29 //绘制线段 30 GL.Begin (GL.LINES); 31 GL.Color (Color.blue); 32 GL.Vertex (new Vector3 (x1 / Screen.width, y1 / Screen.height, z)); 33 GL.Vertex (new Vector3 (x3 / Screen.width, y3 / Screen.height, z)); 34 GL.End (); 35 GL.Begin (GL.LINES); 36 GL.Color (Color.blue); 37 GL.Vertex (new Vector3 (x2 / Screen.width, y1 / Screen.height, z)); 38 GL.Vertex (new Vector3 (x4 / Screen.width, y3 / Screen.height, z)); 39 GL.End (); 40 GL.Begin (GL.LINES); 41 GL.Color (Color.blue); 42 GL.Vertex (new Vector3 (x1 / Screen.width, y2 / Screen.height, z)); 43 GL.Vertex (new Vector3 (x3 / Screen.width, y4 / Screen.height, z)); 44 GL.End (); 45 GL.Begin (GL.LINES); 46 GL.Color (Color.blue); 47 GL.Vertex (new Vector3 (x2 / Screen.width, y2 / Screen.height, z)); 48 GL.Vertex (new Vector3 (x4 / Screen.width, y4 / Screen.height, z)); 49 GL.End (); 50 51 x1 = x3; 52 x2 = x4; 53 y1 = y3; 54 y2 = y4; 55 } 56 GL.PopMatrix (); 57 }
参数分别为: x,y,z 中心点三维坐标, r 圆的半径, accuracy 精度,精度越小,越圆
如有错误，请不吝指教