补充说明:就是bump下,显示不出来凹凸纹理,而displacement下显示过暗,在bump中,我的dU实现如下:
dU = kh * kn * (payload.texture->getColor(payload.tex_coords[0]+1/payload.texture->width,payload.tex_coords[1]).norm()-payload.texture->getColor(payload.tex_coords[0],payload.tex_coords[1]).norm());