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Metal: torpedo cursor is instant with a self-fading comet trail

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The animator cached cursorMode at init, so mtl-cursor-mode (and
mtl-scroll-effect) only updated the global and a live frame kept its
old mode (the default spring), which is why the cursor still moved with
a transition. Propagate the value to live animators immediately.

In torpedo mode the cursor now snaps straight to the target cell (no
spring), and the trail samples carry their own age so the tail fades on
its own ~0.4s after the cursor stops, combining a spatial taper with a
temporal fade so it reads as a comet rather than a uniform bar.
This commit is contained in:
Andros Fenollosa 2026-06-02 14:49:48 +02:00
parent 277b69ddca
commit 0e1e6f983d
3 changed files with 75 additions and 7 deletions
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29
src/mtlfns.m
View file

@ -314,6 +314,23 @@ MODE is an integer 0-7:
NSUInteger m = (NSUInteger)XFIXNAT (mode);
if (m > 7) error ("mtl-cursor-mode: mode must be 0-7");
g_mtl_cursor_mode = (MtlCursorMode)m;
/* Propagate to live animators: each MtlAnimator caches cursorMode at init,
so without this a running frame keeps its old mode (e.g. the default
spring) and the change only takes effect on the next (mtl-enable). */
Lisp_Object tail, frame;
FOR_EACH_FRAME (tail, frame)
{
struct frame *f = XFRAME (frame);
if (!FRAME_LIVE_P (f) || !FRAME_NS_P (f))
continue;
MtlFrameData *fd = mtl_get_frame_data (f);
if (fd && fd.animator)
{
fd.animator.cursorMode = g_mtl_cursor_mode;
fd.animator.trailCount = 0; /* drop any stale trail from old mode */
}
}
return mode;
}
@ -332,6 +349,18 @@ EFFECT is an integer 0-5:
NSUInteger e = (NSUInteger)XFIXNAT (effect);
if (e > 5) error ("mtl-scroll-effect: effect must be 0-5");
g_mtl_scroll_easing = (MtlScrollEasing)e;
/* Propagate to live animators (they cache scrollEasing at init). */
Lisp_Object tail, frame;
FOR_EACH_FRAME (tail, frame)
{
struct frame *f = XFRAME (frame);
if (!FRAME_LIVE_P (f) || !FRAME_NS_P (f))
continue;
MtlFrameData *fd = mtl_get_frame_data (f);
if (fd && fd.animator)
fd.animator.scrollEasing = g_mtl_scroll_easing;
}
return effect;
}

2
src/mtlterm.h
View file

@ -88,6 +88,8 @@ typedef struct mtl_spring {
/* Trail history (torpedo mode) — C arrays cannot be @property */
float trailX[MTL_TRAIL_LEN];
float trailY[MTL_TRAIL_LEN];
/* Seconds since each trail sample was emitted; drives the smooth fade. */
float trailAge[MTL_TRAIL_LEN];
/* Particles (pixiedust, sonicboom, ripple) */
MtlParticle particles[MTL_MAX_PARTICLES];
}

51
src/mtlterm.m
View file

@ -791,6 +791,10 @@ mtl_setup_frame (struct frame *f)
#define SPRING_OMEGA 8.0f /* sqrt(k/m): settles in ~150ms */
/* How long a torpedo trail sample stays visible before it fully fades.
The tail dissipates on its own this many seconds after the cursor stops. */
#define MTL_TRAIL_LIFETIME 0.40f
static void
spring_update (MtlSpring1D *s, float target, float dt)
{
@ -876,8 +880,9 @@ easing_apply (MtlScrollEasing mode, float t)
&& (fabsf(dx) > 1 || fabsf(dy) > 1))
{
NSUInteger slot = (self.trailHead + self.trailCount) % MTL_TRAIL_LEN;
trailX[slot] = self.curTargetX;
trailY[slot] = self.curTargetY;
trailX[slot] = self.curTargetX;
trailY[slot] = self.curTargetY;
trailAge[slot] = 0.0f; /* fresh sample, fully opaque */
if (self.trailCount < g_mtl_trail_len)
self.trailCount++;
else
@ -930,9 +935,8 @@ easing_apply (MtlScrollEasing mode, float t)
BOOL needsComposite = NO;
/* Update spring cursor */
if (self.cursorMode == MTL_CURSOR_SPRING
|| self.cursorMode == MTL_CURSOR_TORPEDO)
/* Update spring cursor (spring mode only; torpedo snaps instantly) */
if (self.cursorMode == MTL_CURSOR_SPRING)
{
MtlSpring1D sx = self.springX, sy = self.springY;
spring_update (&sx, self.curTargetX, dt);
@ -944,6 +948,25 @@ easing_apply (MtlScrollEasing mode, float t)
if (dx > 0.5f || dy > 0.5f) needsComposite = YES;
}
/* Age the torpedo trail so it fades out smoothly on its own. Samples are
pushed oldest-first at trailHead, so the head always holds the oldest one;
retire it once it outlives MTL_TRAIL_LIFETIME. */
if (self.cursorMode == MTL_CURSOR_TORPEDO && self.trailCount > 0)
{
for (NSUInteger i = 0; i < self.trailCount; i++)
{
NSUInteger slot = (self.trailHead + i) % MTL_TRAIL_LEN;
trailAge[slot] += dt;
}
while (self.trailCount > 0
&& trailAge[self.trailHead] >= MTL_TRAIL_LIFETIME)
{
self.trailHead = (self.trailHead + 1) % MTL_TRAIL_LEN;
self.trailCount--;
}
if (self.trailCount > 0) needsComposite = YES;
}
/* Update particles */
if (self.nParticles > 0)
{
@ -1280,9 +1303,23 @@ easing_apply (MtlScrollEasing mode, float t)
for (NSUInteger i = 0; i < tlen; i++)
{
NSUInteger slot = (anim.trailHead + i) % MTL_TRAIL_LEN;
float alpha = (float)(i + 1) / (float)(tlen + 1) * 0.6f;
/* Two combined falloffs so the head stays a sharp instant cursor
and the rest reads as a temporary comet tail:
- spatial: samples nearer the cursor (higher i) are brighter,
so even while moving the tail tapers instead of forming a
uniform bright bar that looks like the cursor sliding;
- temporal: every sample fades with age, so the whole tail
dissipates on its own shortly after the cursor stops. */
float pos = (float)(i + 1) / (float)tlen; /* 0=tail .. 1=head */
float frac = anim->trailAge[slot] / MTL_TRAIL_LIFETIME;
if (frac > 1.0f) frac = 1.0f;
float life = 1.0f - frac;
float alpha = pos * life * life * 0.5f; /* spatial x temporal */
float scale = 0.35f + 0.55f * pos; /* narrow toward the tail */
float tx = anim->trailX[slot], ty = anim->trailY[slot];
float x0=tx, y0=ty, x1=tx+cw, y1=ty+ch;
float iw = cw * scale, ih = ch * scale;
float ox = tx + (cw - iw) * 0.5f, oy = ty + (ch - ih) * 0.5f;
float x0=ox, y0=oy, x1=ox+iw, y1=oy+ih;
typedef struct { float x,y,r,g,b,a; } RV;
float r2=ccr,g2=ccg,b2=ccb;
RV v[6] = {