Skybox image: power-of-two resize; upload at FRAME_RENDER_START

- The material system rejects textures whose dimensions are not multiples of 4
  ("Image dimensions must be multiple of 4!"), so scale the decoded image to
  the next power of two (bilinear). 798x798 -> 1024x1024. The invalid VTF also
  crashed the renderer after the apply.
- Move skybox_update() out of the VGUI paint hook into the FRAME_RENDER_START
  FrameStageNotify stage. ITexture::Download only regenerates bits when the
  material system considers the frame render-safe; during paint it returned
  early, the regenerator never ran (no pixels), and a later upload of the
  empty VTF crashed.
- Log the regenerator entry so the log shows whether the upload path ran.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/hl2h.cpp b/src/hl2h.cpp
index 4ba1af3..28b2995 100644
--- a/src/hl2h.cpp
+++ b/src/hl2h.cpp
@@ -770,6 +770,10 @@ static void hkdFrameStageNotify(void *self, int stage) {
   if (oFrameStageNotify)
     oFrameStageNotify(self, stage);
   if (stage == 5) {
+    // Skybox texture uploads happen here, not in the VGUI paint hook: the
+    // material system only downloads procedural textures on a render-safe
+    // frame stage.
+    skybox_update();
     if (g_silent_restore_pending) {
       g_silent_restore_pending = false;
       if (g_iface.engine) {