7201f6d14c
Now we calculate color in range 800..12000 using an approximation a/x+bx+c for R and G and ((at + b)t + c)t + d) for B. Max absolute error for RGB for non-lut function is less than 0.0001, which is enough to get the same 8 bit/channel color as for OSL with a noticeable performance difference. However there is a slight visible difference between previous non-OSL implementation because of lookup table interpolation and offset-by-one mistake. The previous implementation gave black color outside of soft range (t > 12000), now it gives the same color as for 12000. Also blackbody node without input connected is being converted to value input at shader compile time. Reviewers: dingto, sergey Reviewed By: dingto Subscribers: nutel, brecht, juicyfruit Differential Revision: https://developer.blender.org/D1280