review / rework tiles / quad scheduler / higher resolution for ortho photos

[adam-ce]

• i believe the scheduler now requests tiles, but the quad assembler thinks it's quad ids. so we load one level too much. might be the same for gpu tiles.
• check whether we need quads for anything but geometry.
• textures could go 4 into one array layer (512 instead of 256).

[adam-ce]

tile requests were on the correct level. just one function was named confusingly.

[adam-ce]

we don't even need quads for geometry, i think. we are already pulling the geometry info from textures. so if draw arbitrary high zoom level instances, and store per instance the instance tile id (currently geometry tile id), geometry zoom level and array index, we can find the correct texture -> fetch geometry texture etc.

todo/next:

• test textures instead of UBOs -> textures way faster on android

continue

• implement RGBA32F textures
• tile bounds in texture -> use in vertex shader
• populate and use the instanced data for height lookup
• generate draw list independent of available tiles
• clean up array textures (currently set number of quads)

[adam-ce]

• it seems that such large ubos have terrible perf on android. try switching to textures

[adam-ce]

this produces terribly looking geometrical stair cases:

solutions:

• draw smaller geometries (e.g. 3x3, 5x5, 9x9, .. 33x33) when the height map resolution is not enough (but this complicates drawing)
• moving superfluous vertices to the edge (similar to previous solution, just not creating more geometry types)
• draw the same as before, but descend the zoom pyramid in the fragment shader (works only if all 4 quads are available, uv resolution will drop).
• float16/32 texture with texture filtering

think also about deferred shading (including for alpenite).