Output: Add render progress logging

src/frame.h

@@ -27,6 +27,22 @@ typedef struct {
   size_t vertex_count, triangle_count;
 } FrameLensMesh;
 
+typedef enum {
+  FRAME_SPLAT_PROGRESS_PREFETCH_BEGIN,
+  FRAME_SPLAT_PROGRESS_PREFETCH_END,
+  FRAME_SPLAT_PROGRESS_BEGIN,
+  FRAME_SPLAT_PROGRESS_END
+} FrameSplatProgressStage;
+
+typedef void (*FrameSplatProgressCallback)(void *context,
+                                           FrameSplatProgressStage stage,
+                                           size_t completed, size_t total);
+
+typedef struct {
+  FrameSplatProgressCallback callback;
+  void *context;
+} FrameSplatProgress;
+
 int frame_lens_mesh_build_coarse(FrameLensMesh *mesh, int width, int height,
                                  int cell_pixels, double horizontal_fov_deg);
 int frame_lens_mesh_trace(FrameLensMesh *mesh, const SpacetimeSource *spacetime,
@@ -42,7 +58,8 @@ size_t frame_splat_catalog(const FrameLensMesh *mesh,
                            const PsfKernelCache *psf_cache,
                            int catalog_load_workers,
                            CatalogPrefetchStats *prefetch_stats,
-                           PsfSplatStats *psf_stats);
+                           PsfSplatStats *psf_stats,
+                           const FrameSplatProgress *progress);
 void frame_draw_mesh(const FrameLensMesh *mesh, double *hdr, int width,
                      int height, double gray, double opacity);
 void frame_lens_mesh_destroy(FrameLensMesh *mesh);