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1/7 patch

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Marcin
2025-01-22 14:27:53 +00:00
parent 948642ff33
commit 450d747867
1 changed files with 15 additions and 2 deletions
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17
include/cglm/noise.h
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@@ -176,16 +176,29 @@
/* NOTE: This function is not *quite* analogous to glm__noiseDetail_i2gxyzw
* to try to match the output of glm::perlin. I think it might be a bug in
* in the original implementation, but for now I'm keeping it consistent. -MK
*
* Follow up: The original implementation (glm v 1.0.1) does:
*
* vec<4, T, Q> gx0 = ixy0 * T(1.0 / 7.0);
*
* as opposed to:
*
* vec<4, T, Q> gx0 = ixy0 / T(7);
*
* This ends up mapping to different simd instructions, at least on AMD.
* The delta is tiny but it gets amplified by the rest of the noise function.
* Hence we too need to do `glm_vec4_scale` as opposed to `glm_vec4_divs`, to
* match it. -MK
*/
/* glm__noiseDetail_i2gxyz(vec4 i, vec4 gx, vec4 gy, vec4 gz) */
#define glm__noiseDetail_i2gxyz(ixy, gx, gy, gz) { \
/* gx = ixy / 7.0 */ \
glm_vec4_divs(ixy, 7.0f, gx); /* gx = ixy / 7.0 */ \
glm_vec4_scale(ixy, 1.0f / 7.0f, gx); /* gx = ixy * (1/7.0) */\
\
/* gy = fract(floor(gx0) / 7.0)) - 0.5; */ \
glm_vec4_floor(gx, gy); /* gy = floor(gx) */ \
glm_vec4_divs(gy, 7.0f, gy); /* gy /= 7.0 */ \
glm_vec4_scale(gy, 1.0f / 7.0f, gy); /* gy *= 1 / 7.0 */ \
glm_vec4_fract(gy, gy); /* gy = fract(gy) */ \
glm_vec4_subs(gy, 0.5f, gy); /* gy -= 0.5f */ \
\