shader: introduce shader_active_uniforms()

The existing shader api only supports caller-provided uniforms
and attributes at instantiation time, with no ability to
introspect what uniforms are actually actively present in a given
shader.

This commit adds introspection of the active uniforms for a given
shader at creation time, as well as when reloaded, keeping the
information around to be accessed via shader_active_uniforms().

The immediate impetus for this is supporting runtime discovery of
uniforms present in the shader source, with the intention of
exposing these as sequencer tracks for external manipulation.

1 files changed, 6 insertions, 4 deletions

diff --git a/src/pig.c b/src/pig.c
index 6c11c67..6161b8d 100644
--- a/src/pig.c
+++ b/src/pig.c
@@ -72,10 +72,12 @@ static void randomize_color(v3f_t *color)
 
 static void pig_uniforms_func(shader_t *shader, void *uniforms_ctxt, void *render_ctxt, unsigned n_uniforms, const int *uniforms, const m4f_t *model_x, float alpha)
 {
-	play_t		*play = render_ctxt;
-	pig_t		*pig = uniforms_ctxt;
-	unsigned	t0, t1;
-	float		r = randf();
+	play_t			*play = render_ctxt;
+	pig_t			*pig = uniforms_ctxt;
+	unsigned		t0, t1;
+	float			r = randf();
+	const shader_uniform_t	*active_uniforms;
+	int			n_active_uniforms;
 
 	if (play_ticks_elapsed(play, PLAY_TICKS_TIMER2, 1000)) {
 		if (shader_reload_files(shader) < 0)