feat(webgl): add/update opts for defQuadModel()

BREAKING CHANGE: add/update opts for defQuadModel()

- update callsite in defMultiPass()

packages/webgl/src/geo/quad.ts

@@ -1,22 +1,56 @@
 import { DrawMode, ModelSpec } from "../api/model";
 
-export const defQuadModel = (uv = true): ModelSpec => ({
-    attribs: {
-        position: {
-            data: new Float32Array([-1, -1, 1, -1, -1, 1, 1, 1]),
-            size: 2,
+export interface QuadOpts {
+    /**
+     * Side length of the quad in each direction (always square).
+     *
+     * @defaultValue 2.0
+     */
+    size: number;
+    /**
+     * @defaultValue true
+     */
+    uv: boolean;
+    /**
+     * If true, the quad's position will be centered around (0,0). If false, the
+     * quad's bottom-left corner will be at (0,0).
+     *
+     * @defaultValue true
+     */
+    center: boolean;
+}
+
+export const defQuadModel = (opts?: Partial<QuadOpts>): ModelSpec => {
+    let { size, uv, center } = { size: 2, uv: true, center: true, ...opts };
+    size *= 0.5;
+    const o = center ? 0 : size;
+    return {
+        attribs: {
+            position: {
+                data: new Float32Array([
+                    o - size,
+                    o - size,
+                    o + size,
+                    o - size,
+                    o - size,
+                    o + size,
+                    o + size,
+                    o + size,
+                ]),
+                size: 2,
+            },
+            ...(uv
+                ? {
+                      uv: {
+                          data: new Float32Array([0, 0, 1, 0, 0, 1, 1, 1]),
+                          size: 2,
+                      },
+                  }
+                : null),
         },
-        ...(uv
-            ? {
-                  uv: {
-                      data: new Float32Array([0, 0, 1, 0, 0, 1, 1, 1]),
-                      size: 2,
-                  },
-              }
-            : null),
-    },
-    uniforms: {},
-    shader: <any>null,
-    mode: DrawMode.TRIANGLE_STRIP,
-    num: 4,
-});
+        uniforms: {},
+        shader: <any>null,
+        mode: DrawMode.TRIANGLE_STRIP,
+        num: 4,
+    };
+};

packages/webgl/src/multipass.ts

@@ -87,7 +87,7 @@ export const defMultiPass = (opts: MultipassOpts) => {
         return acc;
     }, <IObjectOf<ITexture>>{});
 
-    const model = compileModel(gl, defQuadModel(false));
+    const model = compileModel(gl, defQuadModel({ uv: false }));
     const models = opts.passes.map((pass) => {
         const m = pass.model ? compileModel(gl, <any>pass.model) : { ...model };
         m.shader = initShader(pass);