Specular uses the same 8-bit factor expansion as diffuse, and attenuation
(with the spot factor) is a second 8-bit factor applied after it, also to
ambient. Exact on gpu/probe exp63 for specular, 99.5% for point lights (the
attenuation's own precision is not matched).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The light and material colors first make an 8-bit product, and N.L becomes an
8-bit s = floor(256 * f), which is expanded like a color before the second
multiply: ((2x + 1) * (2s + 1)) >> 10. Bit exact on gpu/probe exp61-62, apart
from N.L itself being about 2^-15 high on the PSP with a scaled world matrix.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Per pixel, from the interpolated q = 1/w: 16 + log2(slope) - log2(q), both
with the same float-bits log2, plus the bias. Bit exact on gpu/probe
exp58-60, including nearest level rounding.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Sprites interpolate UVs with the same fixed point planes as triangles, and
texture coordinates become texels at 1/16 texel, truncated toward zero, also
in the sampler JIT. Bit exact on gpu/probe exp57 (through mode and transform
mode sprites, nearest and bilinear).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Both use the GE's fixed point depth plane. Color is screen-linear, also in
transform mode, with 8-bit channels as the plane values (gpu/probe exp54). For
perspective UVs, s = u * R(w), t and q = R(w) become 15-bit integers at the
triangle's largest exponent, go through the plane, and u = s * R(q) per pixel
(exp55-56, bit exact at 1/16 texel).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
A white vertex color still gets doubled, and so does replace. Found with
gpu/probe exp53.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The GE lerps the top and bottom texel pairs, truncates each to 8 bits, then lerps
those vertically. Bit exact on gpu/probe exp52 (also in ppsspp-re tools/geprobe).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Measured with gpu/probe exp43-47, bit exact:
- New vertices are interpolated from the inside vertex, t = d_in / (d_in -
d_out) with d = z + w through the GE adder, using the GE's reciprocal;
out - in is truncated to float24 before the multiply by t, and t and each
coordinate use float24 products and adds.
- With one vertex outside, the quad is split from the vertex before it in the
GE's order: (p, a, b) and (p, b, n). The GE takes odd strip triangles in
reverse and fan triangles in order, so SendTriangle now says when the
vertices it gets are reversed from that.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Bit exact against the PSP on every pixel of gpu/probe exp36-41 (over a million
pixels of large, small, steep and slanted triangles):
- Per triangle, the doubled area's 16-bit significand indexes a 256-segment
reciprocal table, linear over each segment's low 8 bits (measured for all
inputs; not the z/w table).
- The x and y depth gradients are fixed point, 14 fractional bits per
subpixel, from the exact edge cross products times that reciprocal.
- The plane is anchored at the leftmost vertex, or the rightmost when the long
edge (top to bottom) is strictly the right side of the triangle.
- Each pixel takes the plane at its center, floored.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Measured with gpu/probe (exp30, exp32, exp34, exp35, exp42), bit exact on
all of it (51911 points through general world, view and perspective
matrices, position and depth):
- The vertex position is truncated to a float24.
- Each product in a matrix row keeps the exact value truncated at a fixed
bit weight, 2^-15 below the two inputs' exponents combined, so a
significand product of 2 or more keeps a 17th bit.
- A row is one multi-operand sum: every product and the translation are
truncated to the bit weight of the term with the largest exponent, added
exactly, and the result becomes a float24. There's no order.
- World, view and projection are combined as (world * view) * projection,
each entry summed the same way and kept as a float24.
The Coded Arms PSP replay gets worse (MSE 26 to 52). Its decals depend on
per-pixel depth, whose interpolation hasn't been measured yet.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The GE samples a pixel's texture coordinates at its center, so a 1:1 sprite
starting at u0 shows texel floor(u0 + 0.5) first (floor(u0 - 0.5) when
mirrored). The fast path truncated u0, half a texel off for fractional UVs.
Measured with gpu/probe; integer UVs are unaffected.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
X and Y now go through the same float24 math as Z: clip coordinates from the
combined matrix (also when lighting needs the world position), the GE's
reciprocal, and the viewport offset added without guard bits, which around
2048 lands on the 1/16 subpixel grid. The 12.4 conversion truncates instead of
rounding up at 10/16.
Triangles are sampled exactly at pixel centers, not 1/16 before them, with left
and top edges inclusive. Sprites start at (x + 6) >> 4 horizontally and
(y + 7) >> 4 vertically and end at (v + 7) >> 4, and their 2x2 loop no longer
treats ties differently by pixel parity. Measured with gpu/probe; against PSP
replays, Coded Arms goes from MSE 33 to 26 and the Test Drive map from 17 to 7.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
With depth clip off, the GE doesn't clip triangles and lines at the near
plane: the part beyond it is drawn with extrapolated depth, and a vertex behind
the camera (w <= 0) culls the whole primitive instead. With it on, they're
clipped, and a vertex that gets clipped away can't cull the primitive by being
outside the screen range (w = 0 included). Rects, which aren't clipped, are
culled by a vertex behind the camera either way. Measured with gpu/probe.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The GE counts a vertex as outside when |z| > w, comparing the float24 clip
coordinates without dividing, and culls a primitive only when all its vertices
are outside, with depth clamp on or off. Points were never culled, and lines,
triangles and rectangles were culled on a single outside vertex with clamp off.
Measured with gpu/probe for every primitive type, both clamp modes and a
range of w.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The GE converts the fog factor to 8 bits per vertex, min(floor(256 * f), 255),
and interpolates that linearly in screen space. Clamping after interpolation
instead was up to 127 levels off on triangles that cross the fog range.
Measured with gpu/probe; points and wacky values still match exactly.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Truncating both terms to the precision of the larger one is clearing the
low 8 + (exponent difference) bits of each, after which a float sum is
exact. Only the products still go through doubles, since a product of two
float24s needs up to 32 bits before it's truncated. Same results.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Measured on hardware (gpu/depth/transformprecision, gpu/depth/precision):
clip Z and W come out of the combined matrix as float24s, z/w uses the
GE's reciprocal, which linearly interpolates 128 table segments and isn't
quite 1/w, and the viewport's z * scale + center adds without guard bits:
the smaller term is truncated to the precision of the larger one.
Fixes the Test Drive Unlimited map (#12786) and the missing background in
Fuuun Shinsengumi Bakumatsuden (from #16131), where vertices land right at
the minimum depth.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The hack skips the game's stretch blit, so the display framebuffer stays
black and savestate thumbnails and screenshots came out empty. Do the
stretch from the source image when reading back the display framebuffer.
AGENTS.md: Commit finished work without asking, push only when asked
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Without SSE or NEON, triangle pixels got the secondary color in place of
the primary one plus it, so lit triangles came out black. It showed as
the "unexplained" known failures on riscv64 and loongarch64, and broke
the new gpu/lighting/shademap there. Reproduced on arm64 by building
without NEON.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Environment map S and T are (N.L + 1) / 2 with L the light's vector as
lighting uses it: from the vertex to the light for point and spot lights,
a zero vector staying zero, and the half vector for a light that does
specular. Whether lighting or the light is enabled still doesn't matter
(gpu/lighting/shademap).
The vertex shader ID now carries the type and computation of the shade
mapping lights (the ubershader reads them from u_lightControl), so both
shader caches get a new version.
Fixes the hair shine in iDOLM@STER SP (#12376).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The viewer is at infinity along view space +z, so in world space, where
lighting happens, it's the view matrix's third column rather than
(0,0,1): turning the camera moves the highlights (gpu/lighting/specular).
The shaders read it from u_view.
In a Need for Speed Carbon frame replayed on a PSP, this and the pow
bring the error of the cars from MSE 957 to 120 (Vulkan).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The GE computes these powers as exp2(e * log2(x)), with log2 and exp2
each a straight line between powers of two (Mitchell's approximation),
and only uses the top 4 bits of the specular coefficient's mantissa.
Through a highlight's falloff a true pow is 10-30 steps of 255 brighter
at the exponents games use. Measured in gpu/lighting/specular.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
- Flush() on an empty queue now trims the state and CLUT rings, since its
callers flush because one is full and push right after.
- BinQueue::Full() uses >=, so an overshoot can't go unnoticed.
- IsExactSelfRender compares against the target the queued draws were
binned for, not gstate, which already has the next one during a flush.
- A depth test without depth writes marks the depth buffer as read.
- The DarkStalkers untextured sprite recomputes the binner state around it.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
These own GPU objects, memory or refcounts in their destructors (or assert
there that they were torn down), so a copy would double-free. Nothing copies
them today; this keeps it that way. The manager base classes cover every
backend's subclass.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
- The block transfer overlap check passed the stride in pixels where bytes
are expected, so it only covered part of the rectangle.
- A selfrender/selfdepth flush in UpdateState dropped the current draw's
pending writes and reads, so later transfers didn't wait for it.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Skipping them is only a speed-up, but it changes how states get batched and
optimized, which changes the rendered output (NBA 2K13 and Virtua Tennis
frame dumps). Keep the old behaviour until that's understood.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
A code space clear frees the functions the current state points to, but
the state was kept as long as the GE registers didn't change. Track the
clear generations and recompute, also when a compile during the state
computation clears the caches.
Also skip the binner flush for compiles on builds without the software
JIT, where Compile() does nothing.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Full-screen clears measured on a PSP (pspautotests gpu/timing/blittiming):
0.49ms on a 16-bit framebuffer whatever is cleared, 0.69ms on 8888, 1.02ms on
8888 with depth. Charging them may help games that spin hard on an empty
screen, but it's off (chargeClearTime) until tried on some. The video blit
cost moves into the same function, now EstimateFillCycles.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The blit cost remembered only the last buffer a decoder wrote into, forever.
Move the texture cache's video list (with its ageing out a few flips after
the last write) into GPUCommon, so the texture cache, the blit cost and
SoftGPU all share one. That also counts both of a double-buffered player's
frames, which exposed that a clear drawn with texturing still enabled was
being charged as a blit - skip clears and draws without texture coordinates.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Movie players like the one in Star Wars: Lethal Alliance present every decoded
frame after a single vblank wait, with no clock or timestamp check, so the
frame rate depends on decode, CSC, ATRAC decode and the GE blit adding up to
more than a vblank. We charged nearly nothing for any of them, so such movies
ran at 60 fps until the ringbuffer's slack ran out.
Costs measured on a PSP with a copy of that player (pspautotests
video/mpeg/playertiming), for a 480x272 frame:
- sceVideocodecDecode: 3.4ms (sceMpegAvcDecode 5.8ms less sceMpegAvcCsc 2.4ms)
- sceMpegBaseCscAvc: 2.4ms, was a flat 4ms
- sceAudiocodecDecode, ATRAC3+ only: 2.5ms per frame
- GE: 9.7ms for a through-mode rectangle blit from a decoded video frame,
charged by area, only for textures in the buffer a decoder last wrote.
GE time also now carries across stall address updates. Before, a list sent
in stalled chunks only had its last chunk's time counted, so sceGeDrawSync
returned 39us after a blit that takes 9.7ms. This affects every game that
builds its lists incrementally, so GE-timing-sensitive games need checking.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
