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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.c
+41 -33
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@@ -93,36 +93,40 @@ I_ B1* prim__alloc(U4 type_width, Str8 type_name) {
#define prim_alloc(type) (type*)prim__alloc(S_(type), slit( stringify(type)))
void
resolve_look_at_c11(MT3_S2S4* look_at, V3_S4* eye, V3_S4* target, V3_S4* up_in) {
// TODO(Ed): Want to interpret this under the lens of Eric Lengyel's geometric algebra
resolve_look_at_c11(MT3_S2S4* look_at, P3_S4* eye, P3_S4* target, V3_S4* up_in) {
// RGA(Lengyel): Build matrix expansion of a rigid transformation. Corresponding motor is not constructed; we write the LA form for GTE.
// Preconditions: eye != target, up_in not collinear with (target - eye).
V3_S4 right, up, forward;
V3_S4 ux, uy, uz;
V3_S4 pos, off;
forward = target[0]; sub_v3s4(& forward, eye[0]);
normalize_v3s4(& forward, & uz);
forward = target[0]; sub_v3s4(& forward, eye[0]); // RGA(Lengyel): Affine point - point = zero-weight direction.
normalize_v3s4(& forward, & uz); // RGA(Lengyel): Normalize the direction bulk. Not finite-point unitization.
cross_v3s4(& uz, up_in, & right); normalize_v3s4(& right, & ux);
cross_v3s4(& uz, & ux, & up); normalize_v3s4(& up, & uy);
cross_v3s4(& uz, up_in, & right); normalize_v3s4(& right, & ux); // RGA(Lengyel): Complement(Wedge(forward, up_in)) -> right axis.
cross_v3s4(& uz, & ux, & up); normalize_v3s4(& up, & uy); // RGA(Lengyel): Complement(Wedge(forward, right)) -> up axis.
// RGA(Lengyel): matrix expansion of the world-to-camera rotation (basis rows).
look_at->m[0][0] = ux.x; look_at->m[0][1] = ux.y; look_at->m[0][2] = ux.z;
look_at->m[1][0] = uy.x; look_at->m[1][1] = uy.y; look_at->m[1][2] = uy.z;
look_at->m[2][0] = uz.x; look_at->m[2][1] = uz.y; look_at->m[2][2] = uz.z;
pos = eye[0]; mul_v3s4(& pos, v3s4(-1,-1,-1));
pos = eye[0]; mul_v3s4(& pos, v3s4(-1,-1,-1)); // RGA(Lengyel): -eye in world coordinates (spatial bulk only; implicit weight is dropped).
// RGA(Lengyel): R * (-eye) is the full matrix translation column.
// Motor translator would store half this displacement in m.xyz; GTE consumes full column.
mul_m3s2_v3s4(look_at, & pos, & off);
trans_m3s2(look_at, & off);
trans_m3s2( look_at, & off);
}
FI_ void camera_look_at_c11(Camera* c, V3_S4* target, V3_S4* up_in) { resolve_look_at_c11(& c->look_at, & c->pos, target, up_in); }
FI_ void camera_look_at_c11(Camera* c, P3_S4* target, V3_S4* up_in) { resolve_look_at_c11(& c->look_at, & c->pos, target, up_in); }
GCC_OPTIMIZATION_DISABLE
void update(PrimitiveArena* pa, U4* ordering_buf)
{
TapeBuilder tb = tb_make(slice_ut_arr(smem.MemTape));
if (1) // Pad Input
// Pad Input
{
tb.used = 0; tb_scope_run(& tb) {
// Grab latest state from bios.
@@ -133,32 +137,10 @@ void update(PrimitiveArena* pa, U4* ordering_buf)
tb_data_(raw, & smem.pad_raw[1]);
tb_data_(state, & smem.pad[1]);
// TODO(Ed): Implement based on below.
tb_emit_(pad_input_cam);
tb_data_(state, & smem.pad[0]);
tb_data_(cam, & smem.cam);
// if (pad0_btn_(Pad_Left)) {
// smem.cam.pos.x -= 50;
// }
// if (pad0_btn_(Pad_Right)) {
// smem.cam.pos.x += 50;
// }
// if (pad0_btn_(Pad_Up)) {
// smem.cam.pos.y -= 50;
// }
// if (pad0_btn_(Pad_Down)) {
// smem.cam.pos.y += 50;
// }
// if (pad0_btn_(Pad_Cross)) {
// smem.cam.pos.z -= 50;
// }
// if (pad0_btn_(Pad_Circle)) {
// smem.cam.pos.z += 50;
// }
// Demo input (not longer using)
// tb_emit_(pad_input_cube_rotation);
// tb_data_(state, & smem.pad[0]);
// tb_data_(cube_rot, & smem.cube.rot);
@@ -197,10 +179,36 @@ void update(PrimitiveArena* pa, U4* ordering_buf)
// Camera look at (Tape)
if (0)
{
MT3_S2S4* look_at = & smem.cam.look_at;
P3_S4* eye = & smem.cam.pos;
V3_S4* up_in = & v3s4(0, -fp_one, 0);
V3_S4 right, up, forward;
V3_S4 ux, uy, uz;
V3_S4 pos, off;
tb.used = 0; tb_scope_run(& tb) {
tb_emit_(resolve_look_at);
// tb_data_();
}
// forward = target[0]; sub_v3s4(& forward, eye[0]); // RGA(Lengyel): Affine point - point = zero-weight direction.
// normalize_v3s4(& forward, & uz); // RGA(Lengyel): Normalize the direction bulk. Not finite-point unitization.
cross_v3s4(& uz, up_in, & right); normalize_v3s4(& right, & ux); // RGA(Lengyel): Complement(Wedge(forward, up_in)) -> right axis.
cross_v3s4(& uz, & ux, & up); normalize_v3s4(& up, & uy); // RGA(Lengyel): Complement(Wedge(forward, right)) -> up axis.
// RGA(Lengyel): matrix expansion of the world-to-camera rotation (basis rows).
look_at->m[0][0] = ux.x; look_at->m[0][1] = ux.y; look_at->m[0][2] = ux.z;
look_at->m[1][0] = uy.x; look_at->m[1][1] = uy.y; look_at->m[1][2] = uy.z;
look_at->m[2][0] = uz.x; look_at->m[2][1] = uz.y; look_at->m[2][2] = uz.z;
pos = eye[0]; mul_v3s4(& pos, v3s4(-1,-1,-1)); // RGA(Lengyel): -eye in world coordinates (spatial bulk only; implicit weight is dropped).
// RGA(Lengyel): R * (-eye) is the full matrix translation column.
// Motor translator would store half this displacement in m.xyz; GTE consumes full column.
mul_m3s2_v3s4(look_at, & pos, & off);
trans_m3s2( look_at, & off);
}
// Draw cube