Reusable 3D Earth globe widget (pure OCaml + WebGL)
Add Scene.projection and Scene.view frame accessors
Allows custom renderers (e.g. conjunction markers) to access the
per-frame projection and view matrices computed by begin_frame,
without recomputing them.
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+14
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webgl/scene.ml
+14
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webgl/scene.ml
···
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(** Globe scene: canvas setup, render loop, and layer compositing.
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Bundles the WebGL boilerplate that every globe app needs:
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canvas/GL init, resize handling, camera, and the correct draw
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order for all layers (stars → earth → grid → orbits → coverage). *)
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Bundles the WebGL boilerplate that every globe app needs: canvas/GL init,
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resize handling, camera, and the correct draw order for all layers (stars →
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earth → grid → orbits → coverage). *)
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open Brr
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open Brr_canvas
···
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let camera t = t.camera
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let orbit t = t.orbit
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let coverage t = t.coverage
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let set_grid_spacing t spacing =
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t.grid <- Some (Grid.v ~spacing t.gl)
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let set_grid_spacing t spacing = t.grid <- Some (Grid.v ~spacing t.gl)
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(* ------------------------------------------------------------------ *)
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(* Per-frame matrices *)
···
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in
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if projection_offset <> 0. then proj.(12) <- projection_offset;
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let projection = Globe.Math.Mat4.to_float_array proj in
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let view =
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Globe.Math.Mat4.to_float_array (Camera.view_matrix t.camera)
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in
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let view = Globe.Math.Mat4.to_float_array (Camera.view_matrix t.camera) in
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Gl.clear t.gl (Gl.color_buffer_bit lor Gl.depth_buffer_bit);
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{ projection; view; width = w; height = h }
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let projection f = f.projection
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let view f = f.view
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(* ------------------------------------------------------------------ *)
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(* Layer drawing with correct compositing order *)
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(* ------------------------------------------------------------------ *)
···
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if layers.show_earth then
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Earth.draw gl t.earth ~projection:p ~view:v ~dim:layers.earth_dim ();
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(* 3. Grid overlay *)
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if layers.show_grid then
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(match t.grid with
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| Some grid ->
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Grid.draw gl grid ~projection:p ~view:v ~color:layers.grid_color
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~alpha:layers.grid_alpha ()
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| None -> ());
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(if layers.show_grid then
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match t.grid with
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| Some grid ->
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Grid.draw gl grid ~projection:p ~view:v ~color:layers.grid_color
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~alpha:layers.grid_alpha ()
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| None -> ());
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(* 4. Orbit trails + satellite dots *)
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if layers.show_orbits then
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Orbit.draw gl t.orbit ~projection:p ~view:v ~dots:layers.orbit_dots;
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webgl/scene.mli
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webgl/scene.mli
···
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(** Globe scene: canvas setup, render loop, and layer compositing.
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Bundles the WebGL boilerplate that every globe app needs.
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Create a scene from a canvas element, then call {!begin_frame}
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and {!draw} each animation frame. *)
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Bundles the WebGL boilerplate that every globe app needs. Create a scene
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from a canvas element, then call {!begin_frame} and {!draw} each animation
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frame. *)
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type t
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(** Opaque scene state: GL context + all renderers. *)
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val v : ?num_points:int -> ?grid_spacing:float -> Brr.El.t -> t
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(** [v ?num_points ?grid_spacing canvas_el] initializes a globe scene
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from a canvas element. Sets up GL context, resize handler, camera,
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and all renderers. *)
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(** [v ?num_points ?grid_spacing canvas_el] initializes a globe scene from a
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canvas element. Sets up GL context, resize handler, camera, and all
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renderers. *)
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val gl : t -> Brr_canvas.Gl.t
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(** [gl t] is the WebGL2 context. *)
···
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(** Per-frame projection and view matrices. *)
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val begin_frame : t -> ?projection_offset:float -> float -> frame
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(** [begin_frame t ?projection_offset dt] updates the camera by [dt]
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seconds, computes projection/view matrices, and clears the frame.
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[projection_offset] shifts the projection center (for sidebar). *)
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(** [begin_frame t ?projection_offset dt] updates the camera by [dt] seconds,
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computes projection/view matrices, and clears the frame. [projection_offset]
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shifts the projection center (for sidebar). *)
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val projection : frame -> float array
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(** [projection frame] is the 4x4 projection matrix as a flat float array. *)
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val view : frame -> float array
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(** [view frame] is the 4x4 view matrix as a flat float array. *)
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(** {1 Layer compositing} *)
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···
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(** [default_layers] has stars and earth on, everything else off. *)
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val draw : t -> frame -> layers -> unit
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(** [draw t frame layers] renders all visible layers in the correct
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compositing order: stars → earth → grid → orbits → coverage. *)
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(** [draw t frame layers] renders all visible layers in the correct compositing
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order: stars → earth → grid → orbits → coverage. *)