This adds a per-layer snippet hook for the texure lookup. Here the
snippet can modify the texture coordinates used for the lookup or
modify the texel resulting from the lookup. This is the first
per-layer hook so this also adds the
COGL_PIPELINE_LAYER_STATE_FRAGMENT_SNIPPETS state and all of the
boilerplate needed to make that work.
Most of the functions used by the pipeline state to manage the snippet
list has been moved into cogl-pipeline-snippet.c so that it can be
shared with the layer state.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
If present, the 'replace' string will be used instead of whatever code
would normally be invoked for that hook point. It will also replace
any previous snippets.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
Each snippet is now given its own function which contains the pre and
post strings. Between these strings the function will chain on to
another function. The generated cogl source is now stored in a
function called cogl_generated_source() which the last snippet will
chain on to. This should make it so that each snippet has its own
namespace for local variables and it can share variables declared in
the pre string in the post string. Hopefully the GLSL compiler will
just inline all of the functions so it shouldn't make much difference
to the compiled output.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
