Image texture code needs some love

[hollasch]

u is mapped to [0, image_width] instead of [0,image_width-1]. Similarly for v, except that it then subtracts 0.001 for some reason.

The subsequent bounds clipping then corrects, but the last horizontal/vertical pixels are lost at this point. Better to clip the U,V coordinates and then apply a correct real→integer transform.

The pixel base address is recomputed three times — it should be calculated in the constructor instead of three times for every pixel access.

[hollasch]

I loved it so much we now have ten kids and twenty head of cattle.