我看到的可能性是，您变化的vTextureIndex的插值效果很差.尝试将其四舍五入到最接近的值，而不是向下:int(vTextureIndex + 0.5).

The possibility I see is poor interpolation of your varying vTextureIndex. Try rounding it to nearest rather than down: int(vTextureIndex + 0.5).

是的，您会认为这不是必需的，但是GPU在允许的所有位置使用大致良好的近似值.

Yes, you would think this wouldn't be necessary, but GPUs use rough good-enough approximations all over the place where they're allowed to.