feat: introduce md2 frame index

Author: demoth

cake/core/src/main/java/org/demoth/cake/stages/Game3dScreen.kt

@@ -218,16 +218,17 @@ class Game3dScreen : KtxScreen, InputProcessor, ServerMessageProcessor {
         for (i in startIndex .. MAX_MODELS) {
             gameConfig[i]?.let { config ->
                 config.value.let {
-                    config.resource = Md2ModelLoader(locator).loadMd2Model(it, skinIndex = 0)
+                    config.resource = Md2ModelLoader(locator).loadMd2Model(it, skinIndex = 0, frameIndex = 0)
                 }
             }
         }
 
         // temporary: load one fixed player model
         playerModel = Md2ModelLoader(locator).loadMd2Model(
-            playerModelPath,
+            modelName = playerModelPath,
             playerSkin = playerSkinPath,
-            0
+            skinIndex = 0,
+            frameIndex = 0
         )!!
 
         gameConfig.getSounds().forEach { config ->

cake/core/src/main/kotlin/org/demoth/cake/modelviewer/Md2ModelLoader.kt

@@ -19,6 +19,7 @@ class Md2ModelLoader(val locator: ResourceLocator) {
         modelName: String,
         playerSkin: String? = null,
         skinIndex: Int,
+        frameIndex: Int,
     ): Model? {
         val findModel = locator.findModel(modelName)
             ?: return null
@@ -28,7 +29,7 @@ class Md2ModelLoader(val locator: ResourceLocator) {
             locator.findSkin(it)
         }
 
-        val first = md2Model.frames.first()
+        val first = md2Model.frames[frameIndex]
 
         val vertexBuffer = md2Model.glCommands.flatMap {
             it.toFloats(first.points)