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- #include <stdbool.h>
- #include <spu_intrinsics.h>
- // shuffle helpers
- #define L0 0x00010203
- #define L1 0x04050607
- #define L2 0x08090a0b
- #define L3 0x0c0d0e0f
- #define R0 0x10111213
- #define R1 0x14151617
- #define R2 0x18191a1b
- #define R3 0x1c1d1e1f
- #define SHUFFLE(l, r, x, y, z, w) si_shufb(l, r, ((qword)(vec_uint4){x, y, z, w}))
- // splat helper
- #define SPLAT(v, idx) si_shufb(v, v, (qword)(vec_uint4)(L ## idx))
- struct matrix43_t
- {
- vec_float4 row0;
- vec_float4 row1;
- vec_float4 row2;
- vec_float4 row3;
- };
- struct aabb_t
- {
- vec_float4 min;
- vec_float4 max;
- };
- struct frustum_t
- {
- vec_float4 planes[6];
- };
- static inline void transform_points_4(qword* dest, qword x, qword y, qword z, const struct matrix43_t* mat)
- {
- #define COMP(c) \
- qword res_ ## c = SPLAT((qword)mat->row3, c); \
- res_ ## c = si_fma(z, SPLAT((qword)mat->row2, c), res_ ## c); \
- res_ ## c = si_fma(y, SPLAT((qword)mat->row1, c), res_ ## c); \
- res_ ## c = si_fma(x, SPLAT((qword)mat->row0, c), res_ ## c); \
- dest[c] = res_ ## c;
- COMP(0);
- COMP(1);
- COMP(2);
- #undef COMP
- }
- static inline qword dot4(qword v, qword x, qword y, qword z)
- {
- qword result = SPLAT(v, 3);
- result = si_fma(SPLAT(v, 2), z, result);
- result = si_fma(SPLAT(v, 1), y, result);
- result = si_fma(SPLAT(v, 0), x, result);
- return result;
- }
- __attribute__((noinline)) bool is_visible(const struct matrix43_t* transform, const struct aabb_t* aabb, const struct frustum_t* frustum)
- {
- qword min = (qword)aabb->min;
- qword max = (qword)aabb->max;
- // get aabb points (SoA)
- qword minmax_x = SHUFFLE(min, max, L0, R0, L0, R0); // x X x X
- qword minmax_y = SHUFFLE(min, max, L1, L1, R1, R1); // y y Y Y
- qword minmax_z_0 = SPLAT(min, 2); // z z z z
- qword minmax_z_1 = SPLAT(max, 2); // Z Z Z Z
- // transform points to world space
- qword points_ws_0[3];
- qword points_ws_1[3];
- transform_points_4(points_ws_0, minmax_x, minmax_y, minmax_z_0, transform);
- transform_points_4(points_ws_1, minmax_x, minmax_y, minmax_z_1, transform);
- // for each plane...
- for (int i = 0; i < 6; ++i)
- {
- qword plane = (qword)frustum->planes[i];
- // calculate 8 dot products
- qword dp0 = dot4(plane, points_ws_0[0], points_ws_0[1], points_ws_0[2]);
- qword dp1 = dot4(plane, points_ws_1[0], points_ws_1[1], points_ws_1[2]);
- // get signs
- qword dp0neg = si_fcgt((qword)(0), dp0);
- qword dp1neg = si_fcgt((qword)(0), dp1);
- if (si_to_uint(si_gb(si_and(dp0neg, dp1neg))) == 15)
- {
- return false;
- }
- }
- return true;
- }
- // simple ortho frustum
- struct frustum_t frustum =
- {
- {
- { 1, 0, 0, 10 },
- { -1, 0, 0, 10 },
- { 0, 1, 0, 10 },
- { 0, -1, 0, 10 },
- { 0, 0, 1, 10 },
- { 0, 0, -1, 10 }
- }
- };
- // small box
- struct aabb_t aabb =
- {
- { -1, -2, -3 },
- { 1, 2, 3 }
- };
- // and some weird matrix
- struct matrix43_t transform =
- {
- { 0.123f, 0.456f, 0.789f },
- { 0.456f, 0.123f, 0.789f },
- { 0.789f, 0.123f, 0.456f },
- { 1.f, -1.f, 1.f }
- };
- void _start()
- {
- is_visible(&transform, &aabb, &frustum);
- si_stop(0);
- }
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