feat: Stabler renderPipeline inference with props placeholder (#157)

Keeping a placeholder for how to handle the data to be later fetched by
`getTileData` is a lot more elegant than just inserting a new module at
the beginning.

Questions:

- Should we make a new type "UnresolvedRasterModule" that explicitly
allows a function as the value as a prop?
- Can we be smart with these generics? Ensure that the type returned
from `getTileData` must be the same as the type passed in to the raster
module prop function?
- Can we improve the type hint of `RasterModule` to say that only
numbers and textures are valid values of the properties object?

Closes #141

Author: kylebarron

README.md

@@ -16,10 +16,13 @@ Fully client-side with direct image loading, no server required.
 ## Features
 
 - Client-side visualization with no server required.
-- Fast, GPU-enabled image processing:
+- GPU-based image processing:
     - Converting color spaces like CMYK, YCbCr, CIELAB to RGB.
     - Removing nodata values
     - Applying colormaps
+    - _Soon_: color correction, nodata masks, spectral band math, pixel filtering, etc.
+- Automatically-inferred render pipelines based on GeoTIFF metadata
+    - Or, customizable render pipelines with _no GPU knowledge required_.
 - GPU-based raster reprojection supports image sources from most projections [^1]
 - Intelligent COG rendering, only fetching the portions of the image required for the current view.
 
@@ -30,7 +33,7 @@ Fully client-side with direct image loading, no server required.
 This monorepo contains the following packages, each of which are published to NPM:
 
 - [`@developmentseed/deck.gl-geotiff`](#developmentseeddeckgl-geotiff)
-- [`@developmentseed/deck.gl-zarr`](#developmentseeddeckgl-zarr)
+- [`@developmentseed/deck.gl-zarr`](#developmentseeddeckgl-zarr) (_soon_)
 - [`@developmentseed/deck.gl-raster`](#developmentseeddeckgl-raster)
 - [`@developmentseed/raster-reproject`](#developmentseedraster-reproject)
 

packages/deck.gl-geotiff/src/geotiff/render-pipeline.ts

@@ -21,6 +21,25 @@ export type TextureDataT = {
   texture: Texture;
 };
 
+/**
+ * A raster module that can be "unresolved", meaning that its props may come
+ * from the result of `getTileData`.
+ *
+ * In this case, one or more of the props may be a function that takes the
+ * `getTileData` result and returns the actual prop value.
+ */
+// TODO: it would be nice to improve the generics here, to connect the type of
+// the props allowed by the module to the return type of this function
+type UnresolvedRasterModule<DataT> =
+  | RasterModule
+  | {
+      module: RasterModule["module"];
+      props?: Record<
+        string,
+        number | Texture | ((data: DataT) => number | Texture)
+      >;
+    };
+
 export function inferRenderPipeline(
   // TODO: narrow type to only used fields
   ifd: ImageFileDirectory,
@@ -61,9 +80,14 @@ function createUnormPipeline(
     SamplesPerPixel,
   } = ifd;
 
-  // Texture initialization will be injected inside of renderTile, once the
-  // tile's data has loaded.
-  const renderPipeline: RasterModule[] = [];
+  const renderPipeline: UnresolvedRasterModule<TextureDataT>[] = [
+    {
+      module: CreateTexture,
+      props: {
+        textureName: (data: TextureDataT) => data.texture,
+      },
+    },
+  ];
 
   // Add NoData filtering if GDAL_NODATA is defined
   const noDataVal = parseGDALNoData(GDAL_NODATA);
@@ -142,14 +166,7 @@ function createUnormPipeline(
   const renderTile: COGLayerProps<TextureDataT>["renderTile"] = (
     tileData: TextureDataT,
   ): RasterModule[] => {
-    const { texture } = tileData;
-    return [
-      {
-        module: CreateTexture,
-        props: { textureName: texture },
-      },
-      ...renderPipeline,
-    ];
+    return renderPipeline.map((m, _i) => resolveModule(m, tileData));
   };
 
   return { getTileData, renderTile };
@@ -208,3 +225,25 @@ function photometricInterpretationToRGB(
       );
   }
 }
+
+/**
+ * If any prop of any module is a function, replace that prop value with the
+ * result of that function
+ */
+function resolveModule<T>(m: UnresolvedRasterModule<T>, data: T): RasterModule {
+  const { module, props } = m;
+
+  if (!props) {
+    return { module };
+  }
+
+  const resolvedProps: Record<string, number | Texture> = {};
+  for (const [key, value] of Object.entries(props)) {
+    const newValue = typeof value === "function" ? value(data) : value;
+    if (newValue !== undefined) {
+      resolvedProps[key] = newValue;
+    }
+  }
+
+  return { module, props: resolvedProps };
+}

packages/deck.gl-raster/src/gpu-modules/types.ts

@@ -1,7 +1,11 @@
+import type { Texture } from "@luma.gl/core";
 import type { ShaderModule } from "@luma.gl/shadertools";
 
 export type RasterModule<
-  PropsT extends Record<string, any> = Record<string, any>,
+  PropsT extends Record<string, number | Texture> = Record<
+    string,
+    number | Texture
+  >,
 > = {
   module: ShaderModule<PropsT>;
   props?: Partial<PropsT>;