Moving std140 code to its own module. Here it can evolve into a class or whatever, and it won't clutter the rest of the code.

2026-04-18 14:19:30 -07:00 · 2021-10-29 08:03:55 -07:00
parent e79e741fcf
commit d4b21a0e4c
2 changed files with 86 additions and 85 deletions
--- a/js/std140.js
+++ b/js/std140.js
@@ -0,0 +1,77 @@
+const supportedLayoutTypes = {
+	["i32"]: { alignAtByte: 1, sizeInBytes: 1, baseType: "i32" },
+	["u32"]: { alignAtByte: 1, sizeInBytes: 1, baseType: "u32" },
+	["f32"]: { alignAtByte: 1, sizeInBytes: 1, baseType: "f32" },
+
+	["atomic<i32>"]: { alignAtByte: 1, sizeInBytes: 1, baseType: "i32" },
+	["vec2<i32>"]: { alignAtByte: 2, sizeInBytes: 2, baseType: "i32" },
+	["vec3<i32>"]: { alignAtByte: 4, sizeInBytes: 3, baseType: "i32" },
+	["vec4<i32>"]: { alignAtByte: 4, sizeInBytes: 4, baseType: "i32" },
+
+	["atomic<u32>"]: { alignAtByte: 1, sizeInBytes: 1, baseType: "u32" },
+	["vec2<u32>"]: { alignAtByte: 2, sizeInBytes: 2, baseType: "u32" },
+	["vec3<u32>"]: { alignAtByte: 4, sizeInBytes: 3, baseType: "u32" },
+	["vec4<u32>"]: { alignAtByte: 4, sizeInBytes: 4, baseType: "u32" },
+
+	["atomic<f32>"]: { alignAtByte: 1, sizeInBytes: 1, baseType: "f32" },
+	["vec2<f32>"]: { alignAtByte: 2, sizeInBytes: 2, baseType: "f32" },
+	["vec3<f32>"]: { alignAtByte: 4, sizeInBytes: 3, baseType: "f32" },
+	["vec4<f32>"]: { alignAtByte: 4, sizeInBytes: 4, baseType: "f32" },
+
+	["mat2x2<f32>"]: { alignAtByte: 2, sizeInBytes: 4, baseType: "f32" },
+	["mat3x2<f32>"]: { alignAtByte: 2, sizeInBytes: 6, baseType: "f32" },
+	["mat4x2<f32>"]: { alignAtByte: 2, sizeInBytes: 8, baseType: "f32" },
+	["mat2x3<f32>"]: { alignAtByte: 4, sizeInBytes: 8, baseType: "f32" },
+	["mat3x3<f32>"]: { alignAtByte: 4, sizeInBytes: 12, baseType: "f32" },
+	["mat4x3<f32>"]: { alignAtByte: 4, sizeInBytes: 16, baseType: "f32" },
+	["mat2x4<f32>"]: { alignAtByte: 4, sizeInBytes: 8, baseType: "f32" },
+	["mat3x4<f32>"]: { alignAtByte: 4, sizeInBytes: 12, baseType: "f32" },
+	["mat4x4<f32>"]: { alignAtByte: 4, sizeInBytes: 16, baseType: "f32" },
+};
+
+const computeStructLayout = (types) => {
+	const entries = [];
+	let byteOffset = 0;
+	for (const type of types) {
+		if (supportedLayoutTypes[type] == null) {
+			throw new Error(`Unsupported type: ${type}`);
+		}
+		const { alignAtByte, sizeInBytes, baseType } = supportedLayoutTypes[type];
+		byteOffset = Math.ceil(byteOffset / alignAtByte) * alignAtByte;
+		entries.push({ baseType, byteOffset });
+		byteOffset += sizeInBytes;
+	}
+
+	// console.log(types);
+	// console.log(entries);
+
+	const size = byteOffset * Float32Array.BYTES_PER_ELEMENT;
+
+	return {
+		entries,
+		size,
+		build: (values, buffer = null) => buildStruct(entries, values, buffer ?? new ArrayBuffer(size)),
+	};
+};
+
+const buildStruct = (entries, values, buffer) => {
+	if (values.length !== entries.length) {
+		throw new Error(`This struct contains ${entries.length} values, and you supplied ${values.length}.`);
+	}
+
+	const views = {
+		i32: new Int32Array(buffer),
+		u32: new Uint32Array(buffer),
+		f32: new Float32Array(buffer),
+	};
+
+	for (let i = 0; i < values.length; i++) {
+		const view = views[entries[i].baseType];
+		const value = values[i];
+		const array = value[Symbol.iterator] == null ? [value] : value;
+		view.set(array, entries[i].byteOffset);
+	}
+	return buffer;
+};
+
+export default computeStructLayout;