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Clip poly now right justified, same behavior as earlier EX3

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Sauraen
2025-09-01 20:26:01 -07:00
parent 09bab6125a
commit 114ce81358
1 changed files with 52 additions and 48 deletions
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f3dex3.s
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@@ -1874,43 +1874,52 @@ g_memset_ovl3:
jr $ra
addi $2, $11, memsetBufferSize
// Each clip condition (clipping plane bit being checked) has three phases that
// occur in this order: find an onscreen vertex, then find the transition from an
// onscreen to offscreen vertex, then find the transition from an offscreen to an
// onscreen vertex. The latter two are the edges which must be subdivided.
CLIP_PHASE_FIND_ON equ 1 // These are these values so that we can use branch
CLIP_PHASE_FIND_ON_TO_OFF equ -1 // instructions to check them, and so that the sign
CLIP_PHASE_FIND_OFF_TO_ON equ 0 // bit represents which condition (on/off) to continue.
// The clipping walk finds the two edges to be subdivided and stores them in temp
// memory at these offsets. There are two of these sets of three pointers contiguously.
CLIP_PTR_ONSCR equ 0 // Onscreen vertex at the end of the edge
CLIP_PTR_OFFSCR equ 2 // Offscreen vertex at the other end of the edge
CLIP_PTR_GEN equ 4 // Generated vertex, where to write the results
CLIP_PTR_COUNT equ 6
clip_after_constants:
.if CFG_PROFILING_B
addi perfCounterB, perfCounterB, 1 // Increment clipped (input) tris count
.endif
sqv vZero[0], (clipPolySgn)($zero) // Clear whole polygon
sh $1, clipPoly + 0 // Write the current three verts
sh $2, clipPoly + 2 // as the initial write polygon
sh $3, clipPoly + 4 //
sb $zero, materialCullMode // In case only/all tri(s) clip then offscreen
li clipMaskIdx, 5 // Will sub 1; 4=screen, 3=+x, 2=-x, 1=+y, 0=-y
li clipAlloc, 0 // Init to no temp verts allocated
// Available locals here: $11, $10, $1, $7, $20, $24
sh $1, clipPoly + 0xA // Initial polygon is right-justified
sh $2, clipPoly + 0xC
sh $3, clipPoly + 0xE
sb $zero, materialCullMode // In case only/all tri(s) clip then offscreen
li clipMaskIdx, 5 // Will sub 1; 4=screen, 3=+x, 2=-x, 1=+y, 0=-y
li clipAlloc, 0 // Init to no temp verts allocated
clip_condlooptop:
addi clipMaskIdx, clipMaskIdx, -1
lbu clipMaskShift, (clipCondShifts)(clipMaskIdx)
addi clipPtrs, rdpCmdBufEndP1, tempClipPtrs // Temp mem in output buffer for vtx ptrs
CLIP_PTR_ONSCR equ 0 // Two of these sets of three pointers
CLIP_PTR_OFFSCR equ 2 // These are the inputs to the subdivision. There's always
CLIP_PTR_GEN equ 4 // two subdivisions, onscreen to offscreen then offscreen to
CLIP_PTR_COUNT equ 6 // onscreen.
li clipWalkCount, 0x18 // Give up if loop traversed the polygon 3x
li clipWalkPhase, 1 // 1 = find on; then -1 = find on to off; then 0 = find off to on
li clipWalkPhase, CLIP_PHASE_FIND_ON
j clip_walk_loop
li clipIdx, 0
li clipIdx, 0xA // Start pos doesn't matter, cause first actual op at on-to-off, and there should be only one of these.
clip_found_on:
li clipWalkPhase, -1 // Change to find on to off
li clipWalkPhase, CLIP_PHASE_FIND_ON_TO_OFF
clip_walk_loop_top:
bnez clipWalkPhase, clip_walk_loop_continue
// Phase 0 = find off to on. This is an offscreen vertex, so remove it.
addi $10, clipIdx, -0xC
bnez clipWalkPhase, clip_walk_loop_continue // find on, or find on to off
// 0 = find off to on. This is an offscreen vertex, so remove it.
addi $10, clipIdx, -2
clip_remove_loop:
lhu $11, (clipPoly + 0xC + 2)($10)
sh $11, (clipPoly + 0xC + 0)($10)
bltz $10, clip_remove_loop
addi $10, $10, 2
sh $zero, (clipPoly + 0xE)
lhu $11, (clipPoly + 0)($10)
sh $11, (clipPoly + 2)($10)
bgtz $10, clip_remove_loop
addi $10, $10, -2
sh $zero, (clipPoly + 0)
// Deallocate it. The first iteration is for if it's in the main vertex buffer,
// in which case the deallocation is a no-op.
li $11, 0xFEFF // 0b...111011111111 (8 set to the right of the 0)
@@ -1920,14 +1929,13 @@ clip_deallocate_loop:
bgez $10, clip_deallocate_loop // First iter: loops if in clipTempVerts
sra $11, $11, 1 // First iter: else, clears ...11101111111 (7)
and clipAlloc, clipAlloc, $11 // Clear vertex allocation bit
addi clipIdx, clipIdx, -2 // Re-process same vertex
clip_walk_loop_continue:
move clipLastVtx, clipCurVtx
clip_walk_loop_skip_vtx:
addi clipWalkCount, clipWalkCount, -1
bltz clipWalkCount, clip_timeout
addi clipIdx, clipIdx, 2
andi clipIdx, clipIdx, 0xE
andi clipIdx, clipIdx, 0xE // Circular addressing
clip_walk_loop:
lhu clipCurVtx, (clipPoly)(clipIdx)
beqz clipCurVtx, clip_walk_loop_skip_vtx // Vertex addr = 0 -> skip
@@ -1936,15 +1944,17 @@ clip_walk_loop:
xor $10, $10, clipWalkPhase // Invert the sign bit for phase -1
bltz $10, clip_walk_loop_top // Nonzero clipping bit = offscreen. Phase 1 and 0, continue if offscreen.
sh clipLastVtx, (CLIP_PTR_ONSCR)(clipPtrs) // For on to off only
bgtz clipWalkPhase, clip_found_on
bgtz clipWalkPhase, clip_found_on // 1 = find on
sh clipCurVtx, (CLIP_PTR_OFFSCR)(clipPtrs) // For on to off only
li $10, 0xC // Insert a space here. The zeros are always on the right,
clip_insert_loop: // regardless of the circular buffer rotation.
lhu $11, (clipPoly + 0)($10)
bltz $10, clip_err_insert
sh $11, (clipPoly + 2)($10)
// Insert a space here. The zeros are always on the left.
blez clipIdx, clip_err_insert // Would crash if continued with clipIdx == 0
li $10, 2
clip_insert_loop:
lhu $11, (clipPoly - 0)($10) // Last iter, unecessarily copies clipIdx left one
sh $11, (clipPoly - 2)($10) // but this is harmless & handles case clipIdx == 2
bne $10, clipIdx, clip_insert_loop
addi $10, $10, -2
addi $10, $10, 2
addi clipIdx, clipIdx, -2 // For temp vtx, then reprocess current vtx. Checked clipIdx > 0 above.
// Allocate a temp vertex
li $11, 0x0080 // 7 zeros to the right
li clipTempVtx, clipTempVerts - vtxSize
@@ -1958,8 +1968,8 @@ clip_allocate_loop:
sh clipTempVtx, (clipPoly)(clipIdx)
sh clipTempVtx, (CLIP_PTR_GEN)(clipPtrs)
addi clipPtrs, clipPtrs, CLIP_PTR_COUNT
bltz clipWalkPhase, clip_walk_loop_continue // Currently on to off
li clipWalkPhase, 0 // Change to find off to on (nop if done)
bltz clipWalkPhase, clip_walk_loop_continue // -1 = on to off
li clipWalkPhase, CLIP_PHASE_FIND_OFF_TO_ON // (nop if done)
sh clipLastVtx, (CLIP_PTR_OFFSCR - CLIP_PTR_COUNT)(clipPtrs) // Swapped for off to on
sh clipCurVtx, (CLIP_PTR_ONSCR - CLIP_PTR_COUNT)(clipPtrs) // Swapped for off to on
clip_do_subdivision:
@@ -2078,7 +2088,7 @@ clip_skipxy:
vmrg cDiffF, cDiffF, $v31[1] // keep frac part of factor, else set to 0xFFFF (max val)
vsubc $v29, cDiffF, vOne[0] // frac part - 1 for carry
vge cDiffI, cDiffI, $v31[2] // 0; If integer part of factor >= 0 (after carry, so overall value >= 0x0000.0001),
j vtx_final_setup_for_clip // Clobbers vcc and accum in !NOC config.
j vtx_final_setup_for_clip // TODO can merge this with vtx_store_for_clip Clobbers vcc and accum in !NOC config.
vmrg cFadeOf, cDiffF, vOne[0] // keep frac part of factor, else set to 1 (min val)
clip_after_final_setup: // This is here because otherwise 3 cycle stall here.
vmudn cFadeOn, cFadeOf, $v31[1] // signed x * -1 = 0xFFFF - unsigned x! Fade factor for on screen vert
@@ -2101,23 +2111,17 @@ clip_next_cond:
bgtz clipMaskIdx, clip_condlooptop // Currently 0 = continue to draw
sh $zero, activeClipPlanes // Only matters if we need to draw
// clipDrawPtr <- clipMaskIdx; currently at 0
// Draws verts in pattern like 0-1-2, 0-2-3, 0-3-4
// Draws verts in pattern like 4-2-3, 4-1-2, 4-0-1
li $ra, clip_draw_tris_loop
li $17, 0xE
clip_draw_find_end_loop:
lhu $11, (clipPolySgn)($17)
beqz $11, clip_draw_find_end_loop
addi $17, $17, -2 // End: points one vtx behind last valid vertex
clip_draw_tris_loop:
sub $11, clipDrawPtr, $17
bgez $11, clip_done // Last drawn tri is with clipDrawPtr one vtx behind $17
lhu $1, (clipPolySgn + 2)($17) // Last valid vertex
lhu $2, (clipPolySgn + 0)(clipDrawPtr)
lhu $3, (clipPolySgn + 2)(clipDrawPtr)
mtc2 $1, $v6[10] // Vertex addresses to vector regs
llv $v7[12], (clipPolySgn)(clipDrawPtr) // $2 to elem 6, $3 to elem 7
lhu $2, (clipPolySgn + 0xA)(clipDrawPtr)
lhu $3, (clipPolySgn + 0xC)(clipDrawPtr)
lhu $1, (clipPolySgn + 0xE)($zero)
beqz $2, clip_done
lsv $v6[10], (clipPolySgn + 0xE)($zero) // +E ($1) to elem 5
ldv $v7[10], (clipPolySgn + 0x8)(clipDrawPtr) // +A ($2) to elem 6, +C ($3) to elem 7
j tri_noinit
addi clipDrawPtr, clipDrawPtr, 2
addi clipDrawPtr, clipDrawPtr, -2
clip_timeout:
bltz clipWalkPhase, clip_next_cond // Timed out in find on to off: all onscreen, nothing to do for this cond