Commit Graph

24 Commits

Author SHA1 Message Date
coldhex 798ad30819 nv2a: Perspective-correct interpolation for w-buffering
z_perspective is true implies w-buffering and then the w-coordinate stored
in the depth buffer should also be interpolated in a perspective-correct
way. We do this by calculating w and setting gl_FragDepth in the fragment
shader.

Since enabling polygon offset and setting values using glPolygonOffset
won't have any effect when manually setting gl_FragDepth for w-buffering,
we introduce the depthOffset variable to obtain similar behaviour (but the
glPolygonOffset factor-argument is currently not emulated.) (Note that
glPolygonOffset is OpenGL implementation-dependent and it might be good to
use depthOffset for z-buffering as well, but this is not done here and we
still use OpenGL/Vulkan zbias functionality.)

This also implements depth clipping and clamping in the fragment shader.
If triangles are clipped, the shadows of the small rocks in Halo 2 Beaver
Creek map can have flickering horizontal lines. The shadows are drawn on
the ground in another pass with the same models as for the ground, but for
some reason with depth clamping enabled. The flickering happens if Xemu
clips the ground triangles, but the exact same shadow triangles are depth
clamped, so there are small differences in the coordinates. The shadows
are drawn with depth function GL_EQUAL so there is no tolerance for any
differences. Clipping in the fragment shader solves the problem because
the ground and shadow triangles remain exactly the same regardless of
depth clipping/clamping. For some performance gain, it might be a good
idea to cull triangles by depth in the geometry shader, but this is not
implemented here.

In the programmable vertex shader we always multiply position output by w
because this improves numerical stability in subsequent floating point
computations by modern GPUs. This usually means that the perspective
divide done by the vertex program gets undone.

The magic bounding constants 5.42101e-020 and 1.884467e+019 are replaced
by 5.421011e-20 and 1.8446744e19, i.e. more decimals added. This makes the
32-bit floating point numbers represent exactly 2^(-64) and 2^64 (raw bits
0x1f800000 and 0x5f800000) which seem more likely the correct values
although testing with hardware was not done to this precision.

Testing indicates that the same RCC instruction magic constants are also
applied to both fixed function and programmable vertex shader w-coordinate
output. This bounding replaces the special test for w==0.0 and abs(w)==inf
which used to set vtx_inv_w=1.0 (which did not match Xbox hardware
behaviour.)
2025-03-08 14:54:18 -07:00
Erik Abair f701573d44 nv2a: Use rounded values for alpha testing 2025-03-05 17:12:14 -07:00
Matt Borgerson 7eba0d3124 nv2a/gl: Update copyright on recently modified files 2025-01-07 17:37:06 -07:00
Matt Borgerson 510c280b05 nv2a/gl: Unify ShaderBinding and ShaderLruNode 2025-01-07 17:35:06 -07:00
Matt Borgerson d76898f63b nv2a: Fix variable shadowing complaints 2025-01-07 00:52:51 -07:00
Matt Borgerson 0e50741c28 ui,xbox: Copyright updates on changed files 2025-01-06 23:06:21 -07:00
Matt Borgerson 75ce25c9b5 nv2a: Define DEBUG_NV2A_*=0 ifndef 2025-01-06 23:05:53 -07:00
Matt Borgerson 3106ea97e5 mcpx: Use new bql_[un]lock functions 2025-01-06 23:05:53 -07:00
Matt Borgerson 5cb65d1791 nv2a: Migrate nv2a_get_offsets to new _get_params model 2025-01-06 23:05:53 -07:00
Matt Borgerson b6d6a4709d nv2a/gl: Use snake case for line width ranges 2024-12-31 01:37:05 -07:00
Matt Borgerson e67f19d03b nv2a/vk,gl: Fix a couple 64b shift/printing bugs 2024-12-31 01:37:05 -07:00
Matt Borgerson ae3fe91223 nv2a/gl: Rebase line width feature 2024-12-31 01:37:05 -07:00
Matt Borgerson 88835a1019 nv2a/vk,gl: Handle case where pline_offset == 0 2024-12-31 01:37:05 -07:00
Matt Borgerson c7f82ab79f nv2a/gl: Fix bind_shaders dgroup 2024-12-31 01:37:05 -07:00
Matt Borgerson ec59148333 nv2a: Normalize unnormalized texture coordinates in shader 2024-12-31 01:37:05 -07:00
Matt Borgerson 792ed56d58 nv2a: Block renderer finalization on display present 2024-12-31 01:37:05 -07:00
Matt Borgerson 25afb8603d nv2a: Handle renderer init errors more gracefully 2024-12-31 01:37:05 -07:00
Matt Borgerson c1bbe39f22 nv2a/gl: Rename some functions for clarity 2024-12-31 01:37:05 -07:00
Matt Borgerson f3b6d50d99 nv2a: Merge renderer init, init_thread methods 2024-12-31 01:37:05 -07:00
Matt Borgerson 98fa394f84 nv2a: Add note about downloading dirty surfaces during flush 2024-12-31 01:37:05 -07:00
Matt Borgerson 4bd0406797 nv2a/gl: Make sure vulkan is not set on ShaderState 2024-12-31 01:37:05 -07:00
Matt Borgerson cd2278dd62 nv2a/gl: Ensure shader_binding exists before dirty check 2024-12-31 01:37:05 -07:00
Matt Borgerson 84dd112186 nv2a/gl: Improve renderer teardown 2024-12-31 01:37:05 -07:00
Matt Borgerson a5385803db nv2a: Add Vulkan renderer 2024-12-31 01:37:05 -07:00