model3d: add m3d implementation / bindings (#589)

libs/model3d/build.zig

@@ -0,0 +1,36 @@
+const std = @import("std");
+
+pub const pkg = std.build.Pkg{
+    .name = "model3d",
+    .source = .{ .path = sdkPath("/src/main.zig") },
+};
+
+pub fn build(b: *std.build.Builder) void {
+    const mode = b.standardReleaseOptions();
+    const target = b.standardTargetOptions(.{});
+    const test_step = b.step("test", "Run library tests");
+    test_step.dependOn(&testStep(b, mode, target).step);
+}
+
+pub fn testStep(b: *std.build.Builder, mode: std.builtin.Mode, target: std.zig.CrossTarget) *std.build.RunStep {
+    const main_tests = b.addTestExe("model3d-tests", "src/main.zig");
+    main_tests.setBuildMode(mode);
+    main_tests.setTarget(target);
+    link(main_tests);
+    main_tests.install();
+    return main_tests.run();
+}
+
+pub fn link(step: *std.build.LibExeObjStep) void {
+    step.addCSourceFile(sdkPath("/src/c/m3d.c"), &.{});
+    step.addIncludePath(sdkPath("/src/c"));
+    step.linkLibC();
+}
+
+fn sdkPath(comptime suffix: []const u8) []const u8 {
+    if (suffix[0] != '/') @compileError("suffix must be an absolute path");
+    return comptime blk: {
+        const root_dir = std.fs.path.dirname(@src().file) orelse ".";
+        break :blk root_dir ++ suffix;
+    };
+}