reorganized source, added test cases for tuning

src/loader-shaders.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"bytes"
+	"log"
+	"log/slog"
+	"path"
+	"strings"
+
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+type ShaderRegistry map[string]*ebiten.Shader
+
+var Shaders = LoadShaders("assets/shaders")
+
+func LoadShaders(dir string) ShaderRegistry {
+	shaders := ShaderRegistry{}
+
+	entries, err := assetfs.ReadDir(dir)
+	if err != nil {
+		log.Fatalf("failed to read shaders dir %s: %s", dir, err)
+	}
+
+	for _, file := range entries {
+		path := path.Join(dir, file.Name())
+		fd, err := assetfs.Open(path)
+		if err != nil {
+			log.Fatalf("failed to open shader file %s: %s", file.Name(), err)
+		}
+		defer fd.Close()
+
+		name := strings.TrimSuffix(file.Name(), ".kg")
+
+		buf := new(bytes.Buffer)
+		buf.ReadFrom(fd)
+
+		shader, err := ebiten.NewShader([]byte(buf.Bytes()))
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		shaders[name] = shader
+
+		slog.Debug("loaded shader asset", "path", path)
+	}
+
+	return shaders
+}