Re: Shader coders?

[Emmanuel Rodriguez <emmanuel rodriguez gmail com>]

On Fri, Apr 24, 2009 at 7:19 PM, Michael Sheldon <mike mikeasoft com> wrote:

Hi Pierre,

Pierre-Luc Beaudoin wrote:

To blur the shadow of markers, I though we could use a shader.  Well, I
don't have that knowledge or the time to learn how to write them :)

 I'm not sure that a shader is really the way to go here, besides the complexity of doing it you'd also be drastically limiting the platforms that libchamplain can work on. A number of free graphics drivers (most notably the intel ones) only have very limited/no shader support. Also the OpenGL|ES 1.x specification doesn't make any provision for shaders as far as I'm aware (2.0 does, but I don't think this is widely implemented in hardware yet).

 I haven't looked at the code/feature in question yet, so I could be mistaken with my assumptions, but why not just use a pre-blurred shadow image (in a similar way to google maps)?

The marker's dimensions are not fixed (harcoded) so it's impossible to have a single static shadow bit map.

Could we use cairo for drawing the shadow?

-- 
Emmanuel Rodriguez