feat(shader-ast-stdlib): add 2D SDF arc/bezier fns

thi-ng · May 5, 2022 · 07bd445 · 07bd445
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diff --git a/packages/shader-ast-stdlib/README.md b/packages/shader-ast-stdlib/README.md
@@ -104,7 +104,7 @@ node --experimental-repl-await
 > const shaderAstStdlib = await import("@thi.ng/shader-ast-stdlib");
 ```
 
-Package sizes (gzipped, pre-treeshake): ESM: 11.05 KB
+Package sizes (gzipped, pre-treeshake): ESM: 11.81 KB
 
 ## Dependencies
 
@@ -443,6 +443,7 @@ for reference.
 
 #### Primitives
 
+- `sdfArc2`
 - `sdfBox2`
 - `sdfBox3`
 - `sdfCircle`
@@ -451,6 +452,7 @@ for reference.
 - `sdfLine3`
 - `sdfPlane2`
 - `sdfPlane3`
+- `sdfQuadratic2`
 - `sdfSphere`
 - `sdfTorus`
 - `sdfTriangle2`

diff --git a/packages/shader-ast-stdlib/src/index.ts b/packages/shader-ast-stdlib/src/index.ts
@@ -53,6 +53,8 @@ export * from "./raymarch/scene.js";
 export * from "./screen/uv.js";
 
 export * from "./sdf/annular.js";
+export * from "./sdf/arc.js";
+export * from "./sdf/bezier.js";
 export * from "./sdf/box.js";
 export * from "./sdf/cylinder.js";
 export * from "./sdf/isec.js";

diff --git a/packages/shader-ast-stdlib/src/sdf/arc.ts b/packages/shader-ast-stdlib/src/sdf/arc.ts
@@ -0,0 +1,43 @@
+import type { Vec2Sym } from "@thi.ng/shader-ast/api/syms";
+import { ternary } from "@thi.ng/shader-ast/ast/controlflow";
+import { defn, ret } from "@thi.ng/shader-ast/ast/function";
+import { vec2 } from "@thi.ng/shader-ast/ast/lit";
+import { gt, madd, mul, neg, sub } from "@thi.ng/shader-ast/ast/ops";
+import { $x, $y } from "@thi.ng/shader-ast/ast/swizzle";
+import { sym } from "@thi.ng/shader-ast/ast/sym";
+import { abs, cos, length, sin } from "@thi.ng/shader-ast/builtin/math";
+
+/**
+ * Returns signed distance from `p` to 2D circular arc with `aperture` (in
+ * [0..π] interval), radius `ra` and `thickness`.
+ *
+ * @remarks
+ * Slightly modified version (easier to use aperture control) of original GLSL
+ * impl by Inigo Quilez:
+ *
+ * - https://www.shadertoy.com/view/wl23RK
+ * - https://iquilezles.org/articles/distfunctions2d/
+ */
+export const sdfArc2 = defn(
+    "float",
+    "sdfArc",
+    ["vec2", "float", "float", "float"],
+    (p, apert, ra, rb) => {
+        let q: Vec2Sym;
+        let sc: Vec2Sym;
+        return [
+            (q = sym(vec2(abs($x(p)), $y(p)))),
+            (sc = sym(vec2(sin(apert), cos(apert)))),
+            ret(
+                sub(
+                    ternary(
+                        gt(mul($y(sc), $x(q)), mul($x(sc), $y(q))),
+                        length(madd(sc, neg(ra), q)),
+                        abs(sub(length(q), ra))
+                    ),
+                    rb
+                )
+            ),
+        ];
+    }
+);
diff --git a/packages/shader-ast-stdlib/src/sdf/bezier.ts b/packages/shader-ast-stdlib/src/sdf/bezier.ts
@@ -0,0 +1,117 @@
+import type { FloatSym, Vec2Sym } from "@thi.ng/shader-ast";
+import { assign } from "@thi.ng/shader-ast/ast/assign";
+import { ifThen } from "@thi.ng/shader-ast/ast/controlflow";
+import { defn, ret } from "@thi.ng/shader-ast/ast/function";
+import {
+    float,
+    FLOAT0,
+    FLOAT1,
+    FLOAT2,
+    vec2,
+} from "@thi.ng/shader-ast/ast/lit";
+import {
+    add,
+    div,
+    gte,
+    lt,
+    madd,
+    mul,
+    neg,
+    sub,
+} from "@thi.ng/shader-ast/ast/ops";
+import { $x, $y } from "@thi.ng/shader-ast/ast/swizzle";
+import { sym } from "@thi.ng/shader-ast/ast/sym";
+import {
+    abs,
+    acos,
+    cos,
+    dot,
+    powf,
+    sign,
+    sin,
+    sqrt,
+} from "@thi.ng/shader-ast/builtin/math";
+import { clamp01 } from "../math/clamp.js";
+import { cross2 } from "../math/cross2.js";
+
+/**
+ * Returns signed distance from `p` to 2D quadratic bezier (given by points A,
+ * B, C).
+ *
+ * @remarks
+ * Ported from original GLSL impl by Inigo Quilez:
+ *
+ * - https://www.shadertoy.com/view/MlKcDD
+ * - https://iquilezles.org/articles/distfunctions2d/
+ */
+export const sdfQuadratic2 = defn(
+    "float",
+    "sdfQuadratic2",
+    ["vec2", "vec2", "vec2", "vec2"],
+    (pos, A, B, C) => {
+        let a: Vec2Sym, b: Vec2Sym, c: Vec2Sym, d: Vec2Sym;
+        let kk: FloatSym, kx: FloatSym, ky: FloatSym, kz: FloatSym;
+        let p: FloatSym, q: FloatSym, p3: FloatSym, q2: FloatSym, h: FloatSym;
+        let m: FloatSym, n: FloatSym, t: FloatSym, v: FloatSym, z: FloatSym;
+        let res: FloatSym, sgn: FloatSym;
+        let x: Vec2Sym, y: Vec2Sym, uv: Vec2Sym;
+        return [
+            (a = sym(sub(B, A))),
+            (b = sym(add(madd(B, -2, A), C))),
+            (c = sym(mul(a, 2))),
+            (d = sym(sub(A, pos))),
+            (kk = sym(div(FLOAT1, dot(b, b)))),
+            (kx = sym(mul(kk, dot(a, b)))),
+            (ky = sym(mul(kk, div(madd(FLOAT2, dot(a, a), dot(d, b)), 3)))),
+            (kz = sym(mul(kk, dot(d, a)))),
+            (res = sym(FLOAT0)),
+            (sgn = sym(FLOAT0)),
+            (p = sym(sub(ky, mul(kx, kx)))),
+            (q = sym(madd(sub(mul(mul(FLOAT2, kx), kx), mul(3, ky)), kx, kz))),
+            (p3 = sym(mul(mul(p, p), p))),
+            (q2 = sym(mul(q, q))),
+            (h = sym(madd(p3, 4, q2))),
+            ifThen(
+                gte(h, FLOAT0),
+                [
+                    assign(h, sqrt(h)),
+                    (x = sym(div(sub(vec2(h, neg(h)), q), FLOAT2))),
+                    (uv = sym(mul(sign(x), powf(abs(x), float(1 / 3))))),
+                    (t = sym(clamp01(sub(add($x(uv), $y(uv)), kx)))),
+                    assign(x, madd(madd(b, t, c), t, d)),
+                    assign(res, dot(x, x)),
+                    assign(sgn, cross2(madd(b, mul(t, FLOAT2), c), x)),
+                ],
+                [
+                    (z = sym(sqrt(neg(p)))),
+                    (v = sym(
+                        div(acos(div(q, mul(mul(p, z), FLOAT2))), float(3))
+                    )),
+                    (m = sym(cos(v))),
+                    (n = sym(mul(sin(v), 1.732050808))),
+                    (uv = sym(
+                        clamp01(
+                            sub(mul(vec2(add(m, m), sub(neg(n), m)), z), kx)
+                        )
+                    )),
+                    (x = sym(madd(madd(b, $x(uv), c), $x(uv), d))),
+                    (y = sym(madd(madd(b, $y(uv), c), $y(uv), d))),
+                    assign(m, dot(x, x)),
+                    assign(n, dot(y, y)),
+                    ifThen(
+                        lt(m, n),
+                        [
+                            assign(res, m),
+                            assign(sgn, cross2(madd(b, mul($x(uv), 2), c), x)),
+                        ],
+                        [
+                            assign(res, n),
+                            assign(sgn, cross2(madd(b, mul($y(uv), 2), c), y)),
+                        ]
+                    ),
+                ]
+            ),
+            ret(mul(sign(sgn), sqrt(res))),
+        ];
+    }
+);
diff --git a/packages/shader-ast-stdlib/tpl.readme.md b/packages/shader-ast-stdlib/tpl.readme.md
@@ -370,6 +370,7 @@ for reference.
 
 #### Primitives
 
+- `sdfArc2`
 - `sdfBox2`
 - `sdfBox3`
 - `sdfCircle`
@@ -378,6 +379,7 @@ for reference.
 - `sdfLine3`
 - `sdfPlane2`
 - `sdfPlane3`
+- `sdfQuadratic2`
 - `sdfSphere`
 - `sdfTorus`
 - `sdfTriangle2`