鉴于现有的两步纹理映射技术对环形物体表面的纹理映射均不适用，为此提出了一种两步纹理映射方法,用于解决环形物体的纹理映射问题。该算法选择圆环表面为中介曲面，首先运用面积等比约束方法将两块相同类型的纹理分别映射到圆环的上下两侧表面，并通过对纹理拼接区域进行插值预处理来消除纹理接缝；然后采用中介表面法向法将圆环表面的纹理进一步映射至物体表面。实验结果表明，该算法可将平面纹理映射至多种环形物体表面，不仅纹理形变小，且保持连续，能够较好地满足虚拟现实与真实感绘制对环形物体表面的纹理映射要求。

As the previous two step texture mapping algorithm does not suit the annular objects,a texture mapping algorithm for the annular objects is proposed.The torus is chosen as the media surface,whose upside and underside are mapped respectively with two pairs of the same style textures applying restraint of equal ratio of areas.The two textures are stitched on the torus using the interpolation technique to avoid the joint.Finally,the media surface normal method is adapted to map the texture from the torus to the object’s surfaces.The experimental results show that the algorithm can be used to map the texture from the plane to most of the Annular Object’s surfaces,on which the rendered texture has little distortion and looks continuous.The proposed method can be used in realistic rendering or VR system to map texture onto the surfaces of annular objects.