feat(shader-ast-stdlib): add oscillator fns

packages/shader-ast-stdlib/src/index.ts

@@ -26,6 +26,7 @@ export * from "./math/mincomp";
 export * from "./math/mix-cubic";
 export * from "./math/mix-quadratic";
 export * from "./math/orthogonal";
+export * from "./math/osc";
 export * from "./math/polar";
 export * from "./math/sincos";
 

packages/shader-ast-stdlib/src/math/osc.ts

@@ -0,0 +1,87 @@
+import type { FnU } from "@thi.ng/api";
+import {
+    abs,
+    float,
+    FLOAT0,
+    FLOAT05,
+    FLOAT1,
+    FLOAT2,
+    FloatTerm,
+    fract,
+    madd,
+    mul,
+    NumericF,
+    sin,
+    step,
+    sub,
+    TAU,
+} from "@thi.ng/shader-ast";
+
+const defOsc =
+    (fn: FnU<FloatTerm>) =>
+    (
+        phase: NumericF,
+        freq: NumericF,
+        amp: NumericF = FLOAT1,
+        dc: NumericF = FLOAT0
+    ) =>
+        madd(fn(mul(float(phase), float(freq))), amp, dc);
+
+/**
+ * Sine oscillator (ported from thi.ng/dsp)
+ *
+ * @param phase - normalized phase
+ * @param freq -
+ * @param amp -
+ * @param dc -
+ */
+export const sinOsc = defOsc((phase) => sin(mul(phase, TAU)));
+
+/**
+ * Sawtooth oscillator (ported from thi.ng/dsp)
+ *
+ * @param phase - normalized phase
+ * @param freq -
+ * @param amp -
+ * @param dc -
+ */
+export const sawOsc = defOsc((phase) => sub(FLOAT1, mul(fract(phase), FLOAT2)));
+
+/**
+ * Triangle oscillator (ported from thi.ng/dsp)
+ *
+ * @param phase - normalized phase
+ * @param freq -
+ * @param amp -
+ * @param dc -
+ */
+export const triOsc = defOsc((phase) =>
+    sub(abs(madd(fract(phase), 4, float(-2))), FLOAT1)
+);
+
+/**
+ * Rect oscillator w/ customizable duty cycle (default: 0.5) (ported from
+ * thi.ng/dsp)
+ *
+ * @param phase - normalized phase
+ * @param freq -
+ * @param amp -
+ * @param dc -
+ * @param duty -
+ */
+export const rectOsc = (
+    phase: NumericF,
+    freq: NumericF,
+    amp: NumericF = FLOAT1,
+    dc: NumericF = FLOAT0,
+    duty: NumericF = FLOAT05
+) =>
+    madd(
+        madd(
+            step(float(duty), fract(mul(float(phase), float(freq)))),
+            FLOAT2,
+            float(-1)
+        ),
+        amp,
+        dc
+    );