Unify ICPP STL onto the shared IB model path

docs/documentation/case.md

@@ -186,12 +186,7 @@ MPI topology is automatically optimized to maximize the parallel efficiency for
 | `tau_e(i)` *         | Real    | Supported             | Elastic stresses.                                            |
 | `hcid` *             | Integer | N/A                   | Hard coded patch id                                          |
 | `cf_val` *           | Real    | Supported             | Surface tension color function value                         |
-| `model_filepath`     | String  | Not Supported         | Path to an STL or OBJ file (not all OBJs are supported).     |
-| `model_scale(i)`     | Real    | Not Supported         | Model's (applied) scaling factor for component $i$.          |
-| `model_rotate(i)`    | Real    | Not Supported         | Model's (applied) angle of rotation about axis $i$.          |
-| `model_translate(i)` | Real    | Not Supported         | Model's $i$-th component of (applied) translation.           |
-| `model_spc`          | Integer | Not Supported         | Number of samples per cell when discretizing the model into the grid. |
-| `model_threshold`    | Real    | Not Supported         | Ray fraction inside the model patch above which the fraction is set to one.|
+| `model_id`           | Integer | Not Supported         | Index into the `stl_models` array (geometry 21)              |
 
 *: These parameters should be prepended with `patch_icpp(j)%` where $j$ is the patch index.
 
@@ -296,11 +291,7 @@ Optimal choice of the value of `smooth_coeff` is case-dependent and left to the
 - `patch_icpp(j)%%alpha(i)`, `patch_icpp(j)%%alpha_rho(i)`, `patch_icpp(j)%%pres`, and `patch_icpp(j)%%vel(i)` define for $j$-th patch the void fraction of `fluid(i)`, partial density of `fluid(i)`, the pressure, and the velocity in the $i$-th coordinate direction.
 These physical parameters must be consistent with fluid material's parameters defined in the next subsection.
 
-- `model_filepath` defines the root directory of the STL or OBJ model file.
-
-- `model_scale`, `model_rotate` and `model_translate` define how the model should be transformed to domain-space by first scaling by `model_scale`, then rotating about the Z, X, and Y axes (using `model_rotate`), and finally translating by `model_translate`.
-
-- `model_spc` and `model_threshold` are ray-tracing parameters. `model_spc` defines the number of rays per cell to render the model. `model_threshold` defines the ray-tracing threshold at which the cell is marked as the model.
+- `model_id` selects the STL/OBJ model for a geometry-21 patch by indexing into the `stl_models` array. The model file, scaling, and translation, and the inside/outside threshold, are configured on that `stl_models` entry (see the `stl_models` section below); a cell is marked inside the model using a winding-number test.
 
 #### Elliptic Smoothing
 
@@ -1169,7 +1160,7 @@ This boundary condition can be used for subsonic inflow (`bc_[x,y,z]%[beg,end]`
 | 18   | 2D Varcircle            | 2     | Y      | Requires `[x,y]_centroid`, `radius`, and `thickness` |
 | 19   | 3D Varcircle            | 3     | Y      | Requires `[x,y,z]_centroid`, `length_z`, `radius`, and `thickness` |
 | 20   | 2D Taylor-Green Vortex  | 2     | N      | Requires `[x,y]_centroid`, `length_x`, `length_y`, `vel(1)`, and `vel(2)` |
-| 21   | Model                   | 2 & 3 | Y      | Imports a Model (STL/OBJ). Requires `model_filepath`. |
+| 21   | Model                   | 2 & 3 | Y      | Imports a Model (STL/OBJ). Requires `model_id`. |
 
 The patch types supported by the MFC are listed in table [Patch Types](#patch-types).
 This includes types exclusive to one-, two-, and three-dimensional problems.