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Prepping for: resolve_look_at impl.

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ed
2026-08-08 23:13:18 -04:00
parent b045856dd6
commit 69f2c0d036
11 changed files with 164 additions and 75 deletions
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code/hello_camera/hello_camera.atom.c
+37 -28
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@@ -180,26 +180,6 @@ internal MipsAtom_(gp_screen_init) atom_info(atom_phase(screen_init), atom_reads
mac_yield(),
};
/* ----- pad_apply_input -----
* Reads pad[0].buttons + pad[0].left_x;
* Applies the input-semantics deltas to cube_rot.y + floor_rot.y:
* - D-pad Left: cube_rot.y += 30, floor_rot.y += 5
* - D-pad Right: cube_rot.y -= 30, floor_rot.y -= 5
* - Analog stick X (dead zone 0x70..0x90):
* cube delta = (0x80 - left_x) >> 2 (range approx -32..+32)
* floor delta = (0x80 - left_x) >> 5 (range approx -4..+4)
* - D-pad + analog deltas add when used together.
*
* Convention:
* pad_state = 0 means no buttons active.
* The fail-safe zero-button value flows through unchanged, so a disconnected/fresh pad produces no rotation.
* The branch_le_zero pattern below matches the existing pad_input_demo convention (atom body lines 248/257).
*
* Signed-delta trick:
* load_byte_u zero-extends left_x to 32 bits; sub_u from 0x80 wraps to a SIGNED two's-complement value in the negative range;
* shift_aright (sra) then correctly sign-extends the shift for both positive (left_x < 0x80) and negative (left_x > 0x80) cases.
* Digital pads publish left_x = 0x80 → delta = 0 → no rotation, so the analog step is naturally a no-op for digital controllers.
*/
typedef Struct_(Binds_PadApplyInput) {
PadState* state;
V3_S2* cube_rot;
@@ -334,10 +314,9 @@ internal MipsAtom_(pad_input_cam) atom_info(atom_bind(Binds_PadInputCam)
load_word(R_T1, R_Cam, O_(Camera,pos.x)), // BD-Slot.
// D-pad Left → cam.pos.x -= 50. and_i fulfills BD-slot for load on R_Cam.
and_i(R_T3, R_T0, Pad_Left), branch_le_zero(R_T3, atom_offset(left_x, exit_left_x)), nop,
and_i(R_T3, R_T0, Pad_Left), branch_le_zero(R_T3, atom_offset(left_x, exit_left_x)), mac_yield_load(),
add_si(R_T1, R_T1, -50), store_word(R_T1, R_Cam, O_(Camera,pos.x)),
atom_label(exit_left_x)
/* D-pad Right → cam.pos.x += 50. Reuses R_T1 from Left. */
and_i(R_T3, R_T0, Pad_Right), branch_le_zero(R_T3, atom_offset(right_x, exit_right_x)), nop,
add_si(R_T1, R_T1, 50), store_word(R_T1, R_Cam, O_(Camera,pos.x)),
@@ -348,7 +327,6 @@ atom_label(exit_right_x)
and_i(R_T3, R_T0, Pad_Up), branch_le_zero(R_T3, atom_offset(up_y, exit_up_y)), nop,
add_si(R_T1, R_T1, -50), store_word(R_T1, R_Cam, O_(Camera,pos.y)),
atom_label(exit_up_y)
/* D-pad Down → cam.pos.y += 50. Reuses R_T1 from Up. */
and_i(R_T3, R_T0, Pad_Down), branch_le_zero(R_T3, atom_offset(down_y, exit_down_y)), nop,
add_si(R_T1, R_T1, 50), store_word(R_T1, R_Cam, O_(Camera,pos.y)),
@@ -359,23 +337,54 @@ atom_label(exit_down_y)
and_i(R_T3, R_T0, Pad_Cross), branch_le_zero(R_T3, atom_offset(cross_z, exit_cross_z)), nop,
add_si(R_T1, R_T1, -50), store_word(R_T1, R_Cam, O_(Camera,pos.z)),
atom_label(exit_cross_z)
/* D-pad Circle → cam.pos.z += 50. Reuses R_T1 from Cross. */
and_i(R_T3, R_T0, Pad_Circle), branch_le_zero(R_T3, atom_offset(circle_z, exit_circle_z)), nop,
add_si(R_T1, R_T1, 50), store_word(R_T1, R_Cam, O_(Camera,pos.z)),
atom_label(exit_circle_z)
mac_yield(),
mac_yield_tail(),
};
enum {
_LookAt_WIP,
R_LookAt = R_T0 atom_reg atom_type(MT3_S2S4*),
R_CamEye = R_T1 atom_reg atom_type(P3_S4*),
R_CamTarget = R_T2 atom_reg atom_type(P3_S4*),
R_WorldUp = R_T3 atom_reg atom_type(V3_S4*),
R_LkAt_Fwdx = R_T4 atom_reg atom_type(V3_S4*),
R_LkAt_Fwdy = R_T5 atom_reg atom_type(V3_S4*),
R_LkAt_Fwdz = R_T6 atom_reg atom_type(V3_S4*),
R_Eye_x = R_T7 atom_reg atom_type(V3_S4*),
R_Eye_y = R_T8 atom_reg atom_type(V3_S4*),
R_Eye_z = R_V0 atom_reg atom_type(V3_S4*),
R_LkAt_Up = R_T5 atom_reg atom_type(V3_S4*),
R_LkAt_Right = R_T6 atom_reg atom_type(V3_S4*),
R_AxisX = R_T7 atom_reg atom_type(V3_S4*),
R_AxisY = R_T8 atom_reg atom_type(V3_S4*),
R_AxisZ = R_T7 atom_reg atom_type(V3_S4*),
};
typedef Struct_(Binds_ResolveLookAt) {
U1 bla;
MT3_S2S4* look_at;
P3_S4* eye;
P3_S4* target;
V3_S4* up_in;
};
internal MipsAtom_(resolve_look_at) atom_info(atom_bind(Binds_ResolveLookAt)) {
add_ui_self(R_TapePtr, S_(Binds_ResolveLookAt)),
load_word(R_LookAt, R_TapePtr, O_(Binds_ResolveLookAt,look_at)),
load_word(R_CamEye, R_TapePtr, O_(Binds_ResolveLookAt,eye)),
load_word(R_CamTarget, R_TapePtr, O_(Binds_ResolveLookAt,target)),
load_word(R_WorldUp, R_TapePtr, O_(Binds_ResolveLookAt,up_in)),
add_ui_self( R_TapePtr, S_(Binds_ResolveLookAt)),
// load look_at and eye, then subtract (get direction), then normalize to unit vector.
mac_load_v3s4(R_LkAt_Fwdx, R_LkAt_Fwdy, R_LkAt_Fwdz, R_LookAt, 0),
mac_load_v3s4(R_Eye_x, R_Eye_y, R_Eye_z, R_CamEye, 0),
mac_sub_v3s4( R_LkAt_Fwdx, R_LkAt_Fwdy, R_LkAt_Fwdz,
R_Eye_x, R_Eye_y, R_Eye_z),
mac_yield(),
};