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authorVito Caputo <vcaputo@pengaru.com>2019-11-20 22:08:49 -0800
committerVito Caputo <vcaputo@pengaru.com>2019-11-20 22:08:49 -0800
commit796b3a8b0669ee5e09c6faba6614e3f228d36595 (patch)
tree60a72760c40b5ecd861f13294b93881875bf7f36 /src/modules/julia
parent7a77cc1a7c6c05c6623d78b5a895f2f004ba6cf9 (diff)
julia: vary divergent threshold
This makes the visualization more interesting by adding more variety.
Diffstat (limited to 'src/modules/julia')
-rw-r--r--src/modules/julia/julia.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/src/modules/julia/julia.c b/src/modules/julia/julia.c
index a83fe00..b35116b 100644
--- a/src/modules/julia/julia.c
+++ b/src/modules/julia/julia.c
@@ -18,6 +18,7 @@ typedef struct julia_context_t {
float imagscale;
float creal;
float cimag;
+ float threshold;
unsigned n_cpus;
} julia_context_t;
@@ -77,7 +78,7 @@ static void julia_destroy_context(void *context)
}
-static inline unsigned julia_iter(float real, float imag, float creal, float cimag, unsigned max_iters)
+static inline unsigned julia_iter(float real, float imag, float creal, float cimag, unsigned max_iters, float threshold)
{
unsigned i;
float newr, newi;
@@ -90,7 +91,7 @@ static inline unsigned julia_iter(float real, float imag, float creal, float cim
newr += creal;
newi += cimag;
- if ((newr * newr + newi * newi) > 4.0)
+ if ((newr * newr + newi * newi) > threshold)
return i;
real = newr;
@@ -125,6 +126,15 @@ static void julia_prepare_frame(void *context, unsigned n_cpus, fb_fragment_t *f
ctxt->imagscale = 0.01f * sinf(ctxt->rr * 3.0f) + 0.01f;
ctxt->creal = (1.01f + (ctxt->realscale * cosf(1.5f * M_PI + ctxt->rr) + ctxt->realscale)) * cosf(ctxt->rr * .3f);
ctxt->cimag = (1.01f + (ctxt->imagscale * sinf(ctxt->rr * 3.0f) + ctxt->imagscale)) * sinf(ctxt->rr);
+
+ /* Vary the divergent threshold, this has been tuned to dwell around 1 a bit since it's
+ * quite different looking, then shoot up to a very huge value approaching FLT_MAX which
+ * is also interesting.
+ */
+ ctxt->threshold = cosf(M_PI + ctxt->rr * .1f) * .5f + .5f;
+ ctxt->threshold *= ctxt->threshold * ctxt->threshold;
+ ctxt->threshold *= 35.f;
+ ctxt->threshold = powf(10.f, ctxt->threshold);
}
@@ -142,7 +152,7 @@ static void julia_render_fragment(void *context, fb_fragment_t *fragment)
/* Complex plane confined to {-1.8 - 1.8} on both axis (slightly zoomed), no dynamic zooming is performed. */
for (imag = 1.8 + -(imagstep * (float)fragment->y), y = fragment->y; y < fragment->y + height; y++, imag += -imagstep) {
for (real = -1.8 + realstep * (float)fragment->x, x = fragment->x; x < fragment->x + width; x++, buf++, real += realstep) {
- *buf = colors[julia_iter(real, imag, ctxt->creal, ctxt->cimag, sizeof(colors) / sizeof(*colors))];
+ *buf = colors[julia_iter(real, imag, ctxt->creal, ctxt->cimag, sizeof(colors) / sizeof(*colors), ctxt->threshold)];
}
buf = ((void *)buf) + fragment->stride;
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