Add engine.detect_common_issues() and run it after 300 frames.

src/graphics/render.nim

@@ -249,6 +249,10 @@ proc draw_all*(self: RenderManager) =
         glUseProgram(0)
         glBindVertexArray(0)
 
+    # Detect common issues after an arbitrary amount of time
+    if self.render_tick == 60 * 5:
+        self.engine.detect_common_issues()
+
 proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: RenderCameraData, pass: int = -1, material_override: Material = nil) =
     if mesh.sqscale < 0.000001:
         mesh.culled_in_last_frame = true

src/myou_engine.nim

@@ -69,6 +69,7 @@ proc newMyouEngine*(
     ): MyouEngine
 proc get_builtin_shader_library*(use_cubemap_prefiltering = true): string
 proc get_builtin_shader_textures*(): Table[string, Texture]
+proc detect_common_issues*(self: MyouEngine)
 # End forward declarations
 
 import std/strutils
@@ -220,3 +221,31 @@ proc loadScene*(self: MyouEngine, uri: string, callback: proc(err: string, scene
     let loader = loaders[0](self)
     loader.openAssetFile(uri)
     loader.loadScene(name, nil, callback)
+
+proc detect_common_issues*(self: MyouEngine) =
+    # TODO: use logging
+    template check(cond: bool, msg: string) =
+        if not cond:
+            echo msg
+            return
+
+    check self.screen.nonNil, "Warning: there is no screen"
+    check self.screen.enabled, "Warning: main screen is not enabled"
+    check self.screen.viewports.len != 0, "Warning: main screen has no viewports"
+    var any_scene_enabled = false
+    for vp in self.screen.viewports:
+        if vp.camera.scene.enabled:
+            any_scene_enabled = true
+    check any_scene_enabled, "Warning: no visible scene is enabled"
+    var any_object_visible = false
+    block ob_vis:
+        for vp in self.screen.viewports:
+            if vp.camera.scene.enabled:
+                for pass in vp.camera.scene.mesh_passes:
+                    for mesh in pass:
+                        if mesh.visible and mesh.materials.len != 0:
+                            # TODO: check culling
+                            # TODO: separate flags to specify why nothing is visible
+                            any_object_visible = true
+                            break ob_vis
+    check any_object_visible, "Warning: no visible object"