Another ghetto solution is to not map to 0 to 255. map to 0 to 254, and then 127 is your 0
On Fri, Jul 30, 2010 at 7:10 AM, Ian Mallett <geometr...@gmail.com> wrote: > Hi, > > Intro: > So, I'm working on computational fluid dynamics, and I need to initialize a > velocity texture, which stores a vector field in an image. Velocity vectors > can have a range of values; each component could be either positive and > negative. The X component goes in the red channel, the Y in the green, and > so on. To store the values, the image maps the range [0,255] to > [-1.0,1.0]. I need to have a surface set to precisely velocity = 0 on all > channels. > > The problem: > Because of this, I need a surface filled with the color 127.5. Obviously, > more than 8 bits per channel are required. To update the texture, I'm using > GL_RGBA32F_ARB, which allocates 32 bits per channel. Unfortunately, the > base image created by PyGame has a value of 127 ≈ -0.00196 velocity. In > practice, this leads to "drift" in the simulation. Can something be done to > send a 32 bit per channel surface filled with 127.5 values to the OpenGL? > > Thanks, > Ian >
