Optimize matrix calculation (#3022)

* optimize matrix calculation * optimize matrix calculation * remove vague changelog of no interest to package consumers Co-authored-by: Paul Connelly <[email protected]>
iTwin · Jan 11, 2022 · d9f1974 · d9f1974
1 parent faab1c3
commit d9f1974
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Showing 2 changed files with 18 additions and 6 deletions.
diff --git a/common/changes/@itwin/core-frontend/optimize-matrix-calculation_2022-01-11-16-46.json b/common/changes/@itwin/core-frontend/optimize-matrix-calculation_2022-01-11-16-46.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@itwin/core-frontend",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@itwin/core-frontend"
+}
diff --git a/core/frontend/src/render/webgl/BranchUniforms.ts b/core/frontend/src/render/webgl/BranchUniforms.ts
@@ -19,6 +19,7 @@ import { UniformHandle } from "./UniformHandle";
 import { Matrix3, Matrix4 } from "./Matrix";
 import { RenderCommands } from "./RenderCommands";
 import { desync, sync, SyncToken } from "./Sync";
+import { System } from "./System";
 import { Target } from "./Target";
 import { ClipStack } from "./ClipStack";
 
@@ -242,16 +243,17 @@ export class BranchUniforms {
     Matrix4d.createTransform(mv, this._mv);
     this._mv32.initFromTransform(mv);
 
-    const inv = this._mv.createInverse();
-    if (undefined !== inv) {
-      const invTr = inv.cloneTransposed();
-      this._mvn32.initFromMatrix3d(invTr.matrixPart());
-    }
-
     // Don't bother computing mvp for instanced geometry - it's not used.
     if (!this._isInstanced) {
       uniforms.projectionMatrix.multiplyMatrixMatrix(this._mv, this._mvp);
       this._mvp32.initFromMatrix4d(this._mvp);
+      if (!System.instance.capabilities.isWebGL2) { // inverse model to view is only used if not instanced and not WebGL2
+        const inv = this._mv.createInverse();
+        if (undefined !== inv) {
+          const invTr = inv.cloneTransposed();
+          this._mvn32.initFromMatrix3d(invTr.matrixPart());
+        }
+      }
     }
 
     return true;