feat(shader-ast-stdlib): add indexTo*() and readIndex*() fns

thi-ng · Jul 6, 2019 · a804c28 · a804c28
1 parent a0af395
commit a804c28
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Showing 4 changed files with 94 additions and 27 deletions.
diff --git a/packages/shader-ast-stdlib/src/index.ts b/packages/shader-ast-stdlib/src/index.ts
@@ -52,4 +52,6 @@ export * from "./sdf/torus";
 export * from "./sdf/tri";
 export * from "./sdf/union";
 
+export * from "./tex/index-coord";
+export * from "./tex/index-uv";
 export * from "./tex/read-index";
diff --git a/packages/shader-ast-stdlib/src/tex/index-coord.ts b/packages/shader-ast-stdlib/src/tex/index-coord.ts
@@ -0,0 +1,30 @@
+import {
+    $x,
+    $y,
+    div,
+    madd,
+    modi,
+    UintTerm,
+    uvec2
+} from "@thi.ng/shader-ast";
+import { UVec2Term } from "@thi.ng/shader-ast/api";
+
+/**
+ * Inline function. Similar to `indexToUV()`, but returns uvec2 in pixel
+ * coords. Not compatible with WebGL1.
+ *
+ * @param i
+ * @param width
+ */
+export const indexToCoord = (i: UintTerm, width: UintTerm) =>
+    uvec2(modi(i, width), div(i, width));
+
+/**
+ * Inline function. Reverse op to `indexToCoord()`.  Not compatible with
+ * WebGL1.
+ *
+ * @param coord
+ * @param width
+ */
+export const coordToIndex = (coord: UVec2Term, width: UintTerm) =>
+    madd($y(coord), width, $x(coord));
diff --git a/packages/shader-ast-stdlib/src/tex/index-uv.ts b/packages/shader-ast-stdlib/src/tex/index-uv.ts
@@ -0,0 +1,55 @@
+import {
+    $x,
+    $y,
+    add,
+    defn,
+    div,
+    float,
+    int,
+    modi,
+    mul,
+    ret,
+    vec2
+} from "@thi.ng/shader-ast";
+
+/**
+ * Converts linearized 2D index `i` into a vec2 UV coord, based on given
+ * texture `size` (in pixels).
+ *
+ * @param i
+ * @param size
+ */
+export const indexToUV = defn(
+    "vec2",
+    "indexToUV",
+    [["int", "i", { prec: "highp" }], ["ivec2"]],
+    (i, size) => [
+        ret(
+            vec2(
+                div(float(modi(i, $x(size))), float($x(size))),
+                div(float(div(i, $x(size))), float($y(size)))
+            )
+        )
+    ]
+);
+
+/**
+ * Inverse operation of `indexToUV()`. Converts vec2 UV coord into
+ * linearized 2D index, based on given texture `width` (in pixels).
+ *
+ * @param i
+ * @param width
+ */
+export const uvToIndex = defn(
+    "int",
+    "uvToIndex",
+    [["vec2"], ["int", "width", { prec: "highp" }]],
+    (uv, width) => [
+        ret(
+            add(
+                int(mul($x(uv), float(width))),
+                int(mul($y(uv), float(mul(width, width))))
+            )
+        )
+    ]
+);
diff --git a/packages/shader-ast-stdlib/src/tex/read-index.ts b/packages/shader-ast-stdlib/src/tex/read-index.ts
@@ -2,32 +2,12 @@ import {
     $x,
     $xy,
     $xyz,
-    $y,
-    defn,
-    div,
-    float,
     IntTerm,
     IVec2Term,
-    modi,
-    ret,
-    Sampler2DSym,
-    texture,
-    vec2
+    texture
 } from "@thi.ng/shader-ast";
-
-export const indexToUV = defn(
-    "vec2",
-    "indexToUV",
-    [["int"], ["ivec2"]],
-    (i, size) => [
-        ret(
-            vec2(
-                div(float(modi(i, $x(size))), float($x(size))),
-                div(float(div(i, $x(size))), float($y(size)))
-            )
-        )
-    ]
-);
+import { Sampler2DTerm } from "@thi.ng/shader-ast/api";
+import { indexToUV } from "./index-uv";
 
 /**
  * Inline function. Returns x component at index `i` in `tex`.
@@ -36,7 +16,7 @@ export const indexToUV = defn(
  * @param i
  * @param size
  */
-export const readIndex1 = (tex: Sampler2DSym, i: IntTerm, size: IVec2Term) =>
+export const readIndex1 = (tex: Sampler2DTerm, i: IntTerm, size: IVec2Term) =>
     $x(texture(tex, indexToUV(i, size)));
 
 /**
@@ -46,7 +26,7 @@ export const readIndex1 = (tex: Sampler2DSym, i: IntTerm, size: IVec2Term) =>
  * @param i
  * @param size
  */
-export const readIndex2 = (tex: Sampler2DSym, i: IntTerm, size: IVec2Term) =>
+export const readIndex2 = (tex: Sampler2DTerm, i: IntTerm, size: IVec2Term) =>
     $xy(texture(tex, indexToUV(i, size)));
 
 /**
@@ -56,7 +36,7 @@ export const readIndex2 = (tex: Sampler2DSym, i: IntTerm, size: IVec2Term) =>
  * @param i
  * @param size
  */
-export const readIndex3 = (tex: Sampler2DSym, i: IntTerm, size: IVec2Term) =>
+export const readIndex3 = (tex: Sampler2DTerm, i: IntTerm, size: IVec2Term) =>
     $xyz(texture(tex, indexToUV(i, size)));
 
 /**
@@ -66,5 +46,5 @@ export const readIndex3 = (tex: Sampler2DSym, i: IntTerm, size: IVec2Term) =>
  * @param i
  * @param size
  */
-export const readIndex4 = (tex: Sampler2DSym, i: IntTerm, size: IVec2Term) =>
+export const readIndex4 = (tex: Sampler2DTerm, i: IntTerm, size: IVec2Term) =>
     texture(tex, indexToUV(i, size));