Add asset, resource system, mesh formats, color, SDL3 display and example game

Asset directory with CMake add_asset (extension dispatched), plain file asset
access, resource/resource manager with async load thread and text loader,
URI utilities, mesh format helpers, generated color header, and example game
hooks wired through the engine.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

tools/color.py

@@ -0,0 +1,70 @@
+# Copyright (c) 2026 Dominic Masters
+#
+# This software is released under the MIT License.
+# https://opensource.org/licenses/MIT
+
+import argparse
+import csv
+import os
+
+parser = argparse.ArgumentParser(description="Color CSV to .h defines")
+parser.add_argument("--csv", required=True, help="Path to color CSV file")
+parser.add_argument("--output", required=True, help="Path to output .h file")
+args = parser.parse_args()
+
+# Load colors
+colors = {}
+with open(args.csv, newline="", encoding="utf-8") as f:
+  reader = csv.DictReader(f)
+  if "name" not in reader.fieldnames:
+    raise ValueError("CSV must have a 'name' column")
+  for row in reader:
+    name = row["name"]
+    r, g, b = row["r"], row["g"], row["b"]
+    a = row["a"] if "a" in row and row["a"] != "" else "1.0"
+    for ch in (r, g, b, a):
+      if not (0.0 <= float(ch) <= 1.0):
+        raise ValueError(f"Color channel {ch!r} for '{name}' out of range [0.0, 1.0]")
+    colors[name] = (r, g, b, a)
+
+# Build output
+out = [
+  "#pragma once",
+  '#include "dusk.h"',
+  "",
+  "typedef float_t    colorchannelf_t;",
+  "typedef uint8_t    colorchannel8_t;",
+  "",
+  "typedef struct { colorchannelf_t r, g, b;    } color3f_t;",
+  "typedef struct { colorchannelf_t r, g, b, a; } color4f_t;",
+  "typedef struct { colorchannel8_t r, g, b;    } color3b_t;",
+  "typedef struct { colorchannel8_t r, g, b, a; } color4b_t;",
+  "typedef color4b_t color_t;",
+  "",
+  "#define color3f(r, g, b)    ((color3f_t){ r, g, b })",
+  "#define color4f(r, g, b, a) ((color4f_t){ r, g, b, a })",
+  "#define color3b(r, g, b)    ((color3b_t){ r, g, b })",
+  "#define color4b(r, g, b, a) ((color4b_t){ r, g, b, a })",
+  "#define color(r, g, b, a)   color4b(r, g, b, a)",
+  "#define colorHex(hex)       color4b(((hex >> 24) & 0xFF), ((hex >> 16) & 0xFF), ((hex >> 8) & 0xFF), (hex & 0xFF))",
+  "",
+]
+
+for name, (r, g, b, a) in colors.items():
+  r8, g8, b8, a8 = (int(float(ch) * 255) for ch in (r, g, b, a))
+  macro = "COLOR_" + name.upper()
+  camel = "".join(p[0].upper() + p[1:].lower() for p in name.split("_"))
+
+  out += [
+    f"// {name}",
+    f"#define {macro}_4B  color4b({r8}, {g8}, {b8}, {a8})",
+    f"#define {macro}_3B  color3b({r8}, {g8}, {b8})",
+    f"#define {macro}_3F  color3f({float(r)}f, {float(g)}f, {float(b)}f)",
+    f"#define {macro}_4F  color4f({float(r)}f, {float(g)}f, {float(b)}f, {float(a)}f)",
+    f"#define {macro}     {macro}_4B",
+    "",
+  ]
+
+os.makedirs(os.path.dirname(args.output), exist_ok=True)
+with open(args.output, "w", encoding="utf-8") as f:
+  f.write("\n".join(out))