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fix(param_slider): 7->5 o'clock arc (50% straight up), seam contract single-sourced, boundary/normDeg/wrap-boundary fixes

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This commit is contained in:
Daniel Harvey
2026-07-27 19:09:51 -04:00
parent 6c0bb4c204
commit cf93d4dc50
3 changed files with 58 additions and 32 deletions
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tests/test_param_slider.cpp
+38 -20
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@@ -11,12 +11,14 @@
// of the handle position; controlAtPoint routing a point to the right control id (toggle whole
// area vs slider track vs knob circle) and MISSING in the label column, a row gap, and
// off-panel. FA4 adds the radial KNOB: computeKnob inscribing the circle in its cell, the
// circular hit-test, the arc angle<->value mapping (min at startDeg, max at endDeg, linear
// midpoint; default = the 6->4 o'clock 300-degree sweep), the needle endpoint on the circle,
// and the vertical-drag delta->value map (up = increase) with clamping at 0/1.
// circular hit-test (boundary exclusive), the arc angle<->value mapping (min at startDeg, max at
// endDeg, linear midpoint; default = the 7->5 o'clock 300-degree sweep with 50% landing at 12
// o'clock), wrap-boundary + un-normalized arc inputs, the needle endpoint on the circle, and
// the vertical-drag delta->value map (up = increase) with clamping at 0/1.
#include "../src/vst/param_slider.h"
#include <cmath>
#include <cstdio>
#include <vector>
@@ -158,7 +160,7 @@ static void testValueAtPointDegenerateTrack() {
// --- knob (FA4) -----------------------------------------------------------------
static bool near(double a, double b, double tol) { return (a - b) < tol && (b - a) < tol; }
static bool nearWithin(double a, double b, double tol) { return (a - b) < tol && (b - a) < tol; }
static void testKnobGeometryInscribesCell() {
// A 44x44 cell at (100,0): center (122,22), radius 22.
@@ -177,20 +179,21 @@ static void testKnobGeometryInscribesCell() {
static void testKnobHitTestCircle() {
const KnobGeometry g = computeKnob(Rect{100, 0, 144, 44}); // center (122,22), r 22
CHECK(knobHitTest(g, 122, 22)); // center
CHECK(knobHitTest(g, 122 + 22, 22)); // on the circle boundary (inclusive)
CHECK(knobHitTest(g, 122, 22)); // center — always hits
CHECK(!knobHitTest(g, 122 + 22, 22)); // exactly on the boundary — boundary exclusive
CHECK(!knobHitTest(g, 122 + 22, 44)); // cell corner: inside the rect, outside the circle
CHECK(!knobHitTest(g, 122, 45)); // just below the circle
CHECK(!knobHitTest(g, 122, 45)); // just below the circle
CHECK(knobHitTest(g, 122 + 21, 22)); // one pixel inside the boundary — hits
CHECK(!knobHitTest(KnobGeometry{}, 0, 0)); // degenerate knob hits nothing
}
static void testKnobDefaultArcIsSixToFourOClock() {
const KnobArc arc; // default: 180 (6 o'clock) clockwise to 120 (4 o'clock)
static void testKnobDefaultArcIsSevenToFiveOClock() {
const KnobArc arc; // default: 210 (7 o'clock) clockwise to 150 (5 o'clock)
CHECK(approx(knobSweepDeg(arc), 300.0));
CHECK(approx(knobValueAngleDeg(arc, 0.0), kKnobArcStartDeg)); // min at 6 o'clock
CHECK(approx(knobValueAngleDeg(arc, 1.0), kKnobArcEndDeg)); // max at 4 o'clock
// Midpoint: halfway around the clockwise sweep -> 180 + 150 = 330.
CHECK(approx(knobValueAngleDeg(arc, 0.5), 330.0));
CHECK(approx(knobValueAngleDeg(arc, 0.0), kKnobArcStartDeg)); // min at 7 o'clock (210°)
CHECK(approx(knobValueAngleDeg(arc, 1.0), kKnobArcEndDeg)); // max at 5 o'clock (150°)
// Midpoint: 210 + 150 = 360 -> normalized to 0 (12 o'clock, straight up).
CHECK(approx(knobValueAngleDeg(arc, 0.5), 0.0));
// Out-of-range values clamp to the arc ends.
CHECK(approx(knobValueAngleDeg(arc, -0.5), kKnobArcStartDeg));
CHECK(approx(knobValueAngleDeg(arc, 1.5), kKnobArcEndDeg));
@@ -207,21 +210,35 @@ static void testKnobArcIsParameterized() {
CHECK(approx(knobSweepDeg(KnobArc{0.0, 0.0}), 360.0));
}
static void testKnobArcWrapBoundary() {
// A 1-degree arc starting at 180: end 181, sweep must be 1, NOT 361.
const KnobArc tiny{180.0, 181.0};
CHECK(approx(knobSweepDeg(tiny), 1.0));
// Un-normalized inputs: start -180 (== 180) sweeping to end 120.
// normDeg(-180) = 180; normDeg(120) = 120; sweep = 120-180 = -60 <= 0 -> 300.
const KnobArc unnorm{-180.0, 120.0};
CHECK(approx(knobSweepDeg(unnorm), 300.0));
CHECK(approx(knobValueAngleDeg(unnorm, 0.0), 180.0)); // min at 6 o'clock
CHECK(approx(knobValueAngleDeg(unnorm, 1.0), 120.0)); // max at 4 o'clock
}
static void testKnobNeedlePointOnCircle() {
const KnobGeometry g = computeKnob(Rect{100, 0, 144, 44}); // center (122,22), r 22
// Default arc, value 0 -> 6 o'clock -> straight DOWN from the center (screen +y).
const KnobPoint p6 = knobNeedlePoint(g, KnobArc{}, 0.0);
CHECK(near(p6.x, 122.0, 1e-6) && near(p6.y, 44.0, 1e-6));
// Default arc, value 0 -> 7 o'clock -> needle points down-left from center.
const KnobPoint p7 = knobNeedlePoint(g, KnobArc{}, 0.0);
// 210° clockwise from 12: sin(210°)=-0.5, cos(210°)=-√3/2 -> x = cx - r/2, y = cy + r*√3/2
CHECK(nearWithin(p7.x, 122.0 + 22.0 * std::sin(210.0 * 3.14159265358979323846 / 180.0), 1e-6));
CHECK(nearWithin(p7.y, 22.0 - 22.0 * std::cos(210.0 * 3.14159265358979323846 / 180.0), 1e-6));
// A 12 o'clock needle points straight UP; 3 o'clock points RIGHT.
const KnobPoint p12 = knobNeedlePoint(g, KnobArc{0.0, 180.0}, 0.0);
CHECK(near(p12.x, 122.0, 1e-6) && near(p12.y, 0.0, 1e-6));
CHECK(nearWithin(p12.x, 122.0, 1e-6) && nearWithin(p12.y, 0.0, 1e-6));
const KnobPoint p3 = knobNeedlePoint(g, KnobArc{0.0, 180.0}, 0.5);
CHECK(near(p3.x, 144.0, 1e-6) && near(p3.y, 22.0, 1e-6));
CHECK(nearWithin(p3.x, 144.0, 1e-6) && nearWithin(p3.y, 22.0, 1e-6));
// Every needle endpoint sits ON the circle.
for (double v : {0.0, 0.25, 0.5, 0.75, 1.0}) {
const KnobPoint p = knobNeedlePoint(g, KnobArc{}, v);
const double dx = p.x - g.centerX, dy = p.y - g.centerY;
CHECK(near(dx * dx + dy * dy, g.radius * g.radius, 1e-6));
CHECK(nearWithin(dx * dx + dy * dy, g.radius * g.radius, 1e-6));
}
}
@@ -297,8 +314,9 @@ int main() {
testValueAtPointDegenerateTrack();
testKnobGeometryInscribesCell();
testKnobHitTestCircle();
testKnobDefaultArcIsSixToFourOClock();
testKnobDefaultArcIsSevenToFiveOClock();
testKnobArcIsParameterized();
testKnobArcWrapBoundary();
testKnobNeedlePointOnCircle();
testKnobDragUpIncreases();
testKnobDragClamps();