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[orx-fcurve] improve handling of absolute hold command

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This commit is contained in:
Edwin Jakobs
2024-05-09 10:41:27 +02:00
parent 4c086d9ff9
commit 15e1b4b04a
3 changed files with 28 additions and 14 deletions
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19
orx-fcurve/README.md
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@@ -6,15 +6,16 @@ They are often used to control a property over time.
The language to express FCurves is similar to SVG's path language.
| Relative command | Absolute command | Description |
|---------------------|-----------------------|-------------------------------------------------------------|
| `m y` | `M y` | move the pen only in the y-direction |
| `h x` | `H x` | hold a value to draw a horizontal line |
| `l x,y` | `L x,y` | line to (x, y) |
| `q x0,y0,x,y` | `Q x0,y0,x,y` | quadratic bezier to (x,y) and control-point (x0, y0) |
| `c x0,y0,x1,y1,x,y` | `C x0,y0,x1,y1,x,y` | cubic bezier to (x,y) and control-points (x0, y0), (x1, y1) |
| `t x,y` | `T x,y` | quadratic smooth to (x, y) |
| `s x1,y1,x,y` | `S x1,y1,x,y` | cubic smooth to (x,y) and control point (x1, y1) |
| Relative command | Absolute command | Description |
|---------------------|---------------------|--------------------------------------------------------------|
| `m y` | `M y` | move the pen only in the y-direction |
| `h x` | | hold a value to draw a horizontal line |
| | `H x` | shift curve in time by x. Can only be used as first command. |
| `l x,y` | `L x,y` | line to (x, y) |
| `q x0,y0,x,y` | `Q x0,y0,x,y` | quadratic bezier to (x,y) and control-point (x0, y0) |
| `c x0,y0,x1,y1,x,y` | `C x0,y0,x1,y1,x,y` | cubic bezier to (x,y) and control-points (x0, y0), (x1, y1) |
| `t x,y` | `T x,y` | quadratic smooth to (x, y) |
| `s x1,y1,x,y` | `S x1,y1,x,y` | cubic smooth to (x,y) and control point (x1, y1) |
## Examples

7
orx-fcurve/src/commonMain/kotlin/FCurve.kt
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@@ -308,11 +308,8 @@ class FCurveBuilder {
if (relative) {
lineTo(x, cursor.y)
} else {
val d = x - cursor.x
require(d >= 0.0) {
"requested to hold until $x, but cursor is already at ${cursor.x}"
}
lineTo(d, cursor.y)
require(segments.isEmpty()) { "absolute hold (H $x) is only allowed when used as first command"}
cursor = cursor.copy(x = x)
}
path += "h$x"
}

16
orx-fcurve/src/commonTest/kotlin/TestFCurve.kt
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@@ -16,4 +16,20 @@ class TestFCurve {
assertEquals(10.5, normalizedSampler(1.0))
assertEquals(10.5, normalizedSampler(-1.0))
}
@Test
fun testAbsoluteHold() {
run {
val text = "H-1 L 5 5"
val fc = fcurve(text)
assertEquals(0.0, fc.value(-1.0))
assertEquals(5.0, fc.value(4.0))
}
run {
val text = "H1 L 5 5"
val fc = fcurve(text)
assertEquals(0.0, fc.value(1.0))
assertEquals(5.0, fc.value(6.0))
}
}
}