fix(core): categorical data in "link" mark misbehaved

Closes #231
genome-spy · Feb 20, 2024 · 14a4d8d · 14a4d8d
1 parent 98feeaf
commit 14a4d8d
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Showing 2 changed files with 22 additions and 1 deletion.
diff --git a/packages/core/src/marks/link.js b/packages/core/src/marks/link.js
@@ -228,7 +228,9 @@ export default class LinkMark extends Mark {
                           attribInfo.divisor
                       ) {
                           attribInfo.offset =
-                              offset * this.arrays[attribute].numComponents * 4; // gl.FLOAT in bytes
+                              offset *
+                              this.arrays[attribute].numComponents *
+                              this.bytesPerElement.get(attribute);
                       }
                   }
                   setBuffersAndAttributes(

diff --git a/packages/core/src/marks/mark.js b/packages/core/src/marks/mark.js
@@ -91,6 +91,16 @@ export default class Mark {
          */
         this.bufferInfo = undefined;
 
+        /**
+         * TWGL's BufferInfo doesn't contain the number of bytes per element,
+         * so we need to keep track of it separately. This is mainly used by
+         * the instancing hack in the link mark.
+         *
+         * @type {Map<string, number>}
+         * @protected
+         */
+        this.bytesPerElement = new Map();
+
         /**
          * @type {import("twgl.js").ProgramInfo}
          * @protected
@@ -788,6 +798,15 @@ export default class Mark {
                 { numElements: vertexData.vertexCount }
             );
             this.bufferInfo.allocatedVertices = vertexData.allocatedVertices;
+
+            for (const [attribute, attributeData] of Object.entries(
+                vertexData.arrays
+            )) {
+                this.bytesPerElement.set(
+                    attribute,
+                    attributeData.data.BYTES_PER_ELEMENT
+                );
+            }
         }
     }