internal/cmd/convertshaders: parallelize compilation

Signed-off-by: Egon Elbre <egonelbre@gmail.com>

internal/cmd/convertshaders/workdir.go

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type WorkDir string
+
+func (wd WorkDir) Dir(path string) WorkDir {
+	dirname := filepath.Join(string(wd), path)
+	if err := os.Mkdir(dirname, 0755); err != nil {
+		if !os.IsExist(err) {
+			fmt.Fprintf(os.Stderr, "failed to create %q: %v\n", dirname, err)
+		}
+	}
+	return WorkDir(dirname)
+}
+
+func (wd WorkDir) Path(path ...string) (fullpath string) {
+	return filepath.Join(string(wd), strings.Join(path, "."))
+}
+
+func (wd WorkDir) WriteFile(path string, data []byte) error {
+	err := ioutil.WriteFile(path, data, 0644)
+	if err != nil {
+		return fmt.Errorf("unable to create %v: %w", path, err)
+	}
+	return nil
+}