cogl-pipeline: Add support for setting uniform values

This adds the following new public experimental functions to set
uniform values on a CoglPipeline:

void
cogl_pipeline_set_uniform_1f (CoglPipeline *pipeline,
                              int uniform_location,
                              float value);
void
cogl_pipeline_set_uniform_1i (CoglPipeline *pipeline,
                              int uniform_location,
                              int value);
void
cogl_pipeline_set_uniform_float (CoglPipeline *pipeline,
                                 int uniform_location,
                                 int n_components,
                                 int count,
                                 const float *value);
void
cogl_pipeline_set_uniform_int (CoglPipeline *pipeline,
                               int uniform_location,
                               int n_components,
                               int count,
                               const int *value);
void
cogl_pipeline_set_uniform_matrix (CoglPipeline *pipeline,
                                  int uniform_location,
                                  int dimensions,
                                  int count,
                                  gboolean transpose,
                                  const float *value);

These are similar to the old functions used to set uniforms on a
CoglProgram. To get a value to pass in as the uniform_location there
is also:

int
cogl_pipeline_get_uniform_location (CoglPipeline *pipeline,
                                    const char *uniform_name);

Conceptually the uniform locations are tied to the pipeline so that
whenever setting a value for a new pipeline the application is
expected to call this function. However in practice the uniform
locations are global to the CoglContext. The names are stored in a
linked list where the position in the list is the uniform location.

The global indices are used so that each pipeline can store a mask of
which uniforms it overrides. That way it is quicker to detect which
uniforms are different from the last pipeline that used the same
CoglProgramState so it can avoid flushing uniforms that haven't
changed. Currently the values are not actually compared which means
that it will only avoid flushing a uniform if there is a common
ancestor that sets the value (or if the same pipeline is being flushed
again - in which case the pipeline and its common ancestor are the
same thing).

The uniform values are stored in the big state of the pipeline as a
sparse linked list. A bitmask stores which values have been overridden
and only overridden values are stored in the linked list.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/cogl/cogl-context-private.h b/cogl/cogl-context-private.h
index df0aa4a7..8125e7bb 100644
--- a/cogl/cogl-context-private.h
+++ b/cogl/cogl-context-private.h
@@ -258,6 +258,14 @@ struct _CoglContext
     [COGL_FLAGS_N_LONGS_FOR_SIZE (COGL_WINSYS_FEATURE_N_FEATURES)];
   void *winsys;
 
+  /* List of names of uniforms. These are used like quarks to give a
+     unique number to each uniform name except that we ensure that
+     they increase sequentially so that we can use the id as an index
+     into a bitfield representing the uniforms that a pipeline
+     overrides from its parent */
+  GSList *uniform_names;
+  int n_uniform_names;
+
   /* This defines a list of function pointers that Cogl uses from
      either GL or GLES. All functions are accessed indirectly through
      these pointers rather than linking to them directly */