diff options
Diffstat (limited to 'src/modules/shapes/shapes.c')
| -rw-r--r-- | src/modules/shapes/shapes.c | 47 |
1 files changed, 4 insertions, 43 deletions
diff --git a/src/modules/shapes/shapes.c b/src/modules/shapes/shapes.c index 3943652..b32d7ce 100644 --- a/src/modules/shapes/shapes.c +++ b/src/modules/shapes/shapes.c @@ -238,45 +238,6 @@ static void shapes_prepare_frame(til_module_context_t *context, til_stream_t *st } -/* simple approximation taken from https://mazzo.li/posts/vectorized-atan2.html */ -static inline float atan_scalar_approximation(float x) { - /* TODO: this is probably more terms/precision than needed, but when I try just dropping some, - * the circle+slight pinches gets artifacts. So leaving for now, probably needs slightly different - * values for fewer terms. - */ - float a1 = 0.99997726f; - float a3 = -0.33262347f; - float a5 = 0.19354346f; - float a7 = -0.11643287f; - float a9 = 0.05265332f; - float a11 = -0.01172120f; - float x_sq = x*x; - - return x * (a1 + x_sq * (a3 + x_sq * (a5 + x_sq * (a7 + x_sq * (a9 + x_sq * a11))))); -} - - -static float atan2_approx(float y, float x) { - // Ensure input is in [-1, +1] - int swap = fabs(x) < fabs(y); - float atan_input = (swap ? x : y) / (swap ? y : x); - - // Approximate atan - float res = atan_scalar_approximation(atan_input); - - // If swapped, adjust atan output - res = swap ? (atan_input >= 0.0f ? M_PI_2 : -M_PI_2) - res : res; - - // Adjust quadrants - if (x < 0.0f && y >= 0.0f) - res = M_PI + res; // 2nd quadrant - else if (x < 0.0f && y < 0.0f) - res = -M_PI + res; // 3rd quadrant - - return res; -} - - static void shapes_render_fragment(til_module_context_t *context, til_stream_t *stream, unsigned ticks, unsigned cpu, til_fb_fragment_t **fragment_ptr) { shapes_context_t *ctxt = (shapes_context_t *)context; @@ -337,7 +298,7 @@ static void shapes_render_fragment(til_module_context_t *context, til_stream_t * YYY = Y * Y; if (!radcache->initialized) { for (unsigned x = xstart; x < xend; x++, X++, XX += s) { - float a = rads[y * radcache->width + x] = atan2_approx(YY, XX); + float a = rads[y * radcache->width + x] = atan2f(YY, XX); if (YYY+X*X < r_sq * (1.f - fabsf(cosf(n_pinches * a + pinch)) * pinch_s)) til_fb_fragment_put_pixel_unchecked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, 0xffffffff); /* TODO: stop relying on checked for clipping */ @@ -378,7 +339,7 @@ static void shapes_render_fragment(til_module_context_t *context, til_stream_t * YYYY = YY * YY; if (!radcache->initialized) { for (unsigned x = xstart; x < xend; x++, XX += s) { - float a = rads[y * radcache->width + x] = atan2_approx(YY, XX); + float a = rads[y * radcache->width + x] = atan2f(YY, XX); float r = cosf(n_points * (a + spin)) * .5f + .5f; r *= 1.f - fabsf(cosf(n_pinches * (a + pinch))) * pinch_s; @@ -426,7 +387,7 @@ static void shapes_render_fragment(til_module_context_t *context, til_stream_t * X = -(size >> 1) + xskip; if (!radcache->initialized) { for (unsigned x = xstart; x < xend; x++, X++, XX += s) { - float a = rads[y * radcache->width + x] = atan2_approx(YY, XX); + float a = rads[y * radcache->width + x] = atan2f(YY, XX); if (abs(Y) + abs(X) < r * (1.f - fabsf(cosf(n_pinches * a + pinch)) * pinch_s)) til_fb_fragment_put_pixel_unchecked(fragment, TIL_FB_DRAW_FLAG_TEXTURABLE, x, y, 0xffffffff); @@ -466,7 +427,7 @@ static void shapes_render_fragment(til_module_context_t *context, til_stream_t * YYYY = YY * YY; if (!radcache->initialized) { for (unsigned x = xstart; x < xend; x++, XX += s) { - float a = rads[y * radcache->width + x] = atan2_approx(YY, XX); + float a = rads[y * radcache->width + x] = atan2f(YY, XX); float r = (M_2_PI * asinf(sinf(n_points * (a + spin)) * .5f + .5f)) * .5f + .5f; /* ^^^^^^^^^^^^^^^^^^^ approximates a triangle wave */ |