MacOS build - lines and points rendered differently, too many layers warnings

[hn-88]

Gemini3 Pro says -

It is great to hear that the crash is resolved!

Here are the explanations and suggestions for the three remaining issues you are seeing on macOS. These are generally due to differences in how the macOS OpenGL driver handles the "Core Profile" specification compared to Windows (NVIDIA/AMD) drivers.

1. Warning: "Too many layers are enabled"

The Cause:
This happens during Level-of-Detail (LOD) transitions (zooming in/out). To smooth out the transition, OpenSpace tries to blend the textures from the current chunk with its parent or children. This requires binding many textures simultaneously (Color, Height, Night, Water, Overlays).

• Windows/NVIDIA: Usually supports 32 or more Texture Image Units in fragment shaders.
• macOS: Often limits this to 16 Texture Image Units per shader stage (GL_MAX_TEXTURE_IMAGE_UNITS).

If you have Color (3 textures for blending) + Height (3) + Night (3) + Water (3) + Overlays (3), you hit 15. Add atmospheric tables or shadows, and you exceed the limit of 16. The warning appears when the LOD blending pushes the count over the limit.

The Fix / Workaround:
You cannot increase the hardware limit, but you can reduce the texture usage in the OpenSpace GUI:

1. Open the On-Screen GUI.
2. Go to Scene -> Earth (or the affected planet) -> Renderable -> Layers.
3. Disable layer groups you don't strictly need (e.g., Night Layers, Overlays, or Water Masks).
4. Unchecking these reduces the number of textures the shader attempts to bind, eliminating the warning and potential rendering artifacts.

---

2. Lines on RenderableTrails are thinner

The Cause:
This is a strict limitation of the macOS OpenGL driver.

• The OpenGL "Core Profile" specification deprecated line widths greater than 1.0.
• Windows/Linux drivers generally ignore this deprecation and allow thick lines anyway.
• macOS drivers strictly enforce it. Any glLineWidth(val) where val > 1.0 is ignored and rendered as 1 pixel wide.

The Fix:
There is no configuration fix for this. The only way to get thick lines on macOS is for the application (OpenSpace) to render lines as "volumetric lines" (using triangles/billboards) instead of standard GL lines. This requires C++ source code changes in the RenderableTrail class.

• Suggestion: You can try increasing the opacity or brightness of the trails in the GUI to make them more visible despite being thin.

---

3. Galaxy Points are Bigger

The Cause:
This is likely due to High-DPI (Retina) scaling.

• macOS Retina screens use a backing scaling factor (usually 2.0).
• OpenSpace detects this and multiplies gl_PointSize by the scaling factor so points don't look tiny.
• However, sometimes this logic interacts poorly with the specific "Billboarding" shader used for galaxies, resulting in points that are double the intended size.

The Fix:
You can manually adjust the scale in the GUI:

1. Open the On-Screen GUI.
2. Navigate to the Galaxy object (e.g., Scene -> MilkyWay or DigitalUniverse -> Galaxies).
3. Look for a property named Point Size, Magnitude, or Scale.
4. Reduce the value (try halving it) until it matches the look you expect.

If you are modifying the shader code (renderablegalaxy_fs.glsl or similar), look for where gl_PointSize is set and divide it by the window content scale factor if it seems redundant.

[hn-88]

1. One workaround for thicker trails is to use Points and Lines or Points in the trail properties. Points sizing works on Mac.
2. Too many layers error comes when we zoom out of earth and other objects become enabled, I think. So, just disabling Earth layers is not sufficient - need to check which other renderables are enabling layers.