Add WebGL FPS cap and texture word reveal

public/js/book-pagination-module.js

@@ -77,9 +77,12 @@ class BookPaginationModule extends BaseModule {
 
             const layout = this.layoutTextBlock(block, type);
             if (!layout?.lines?.length) return;
+            let blockWordCursor = 0;
+            cursorLine += layout.topSpaceLines;
 
             layout.lines.forEach((line) => {
                 const geometry = this.getLineGeometry(cursorLine);
+                const lineWordCount = line.nodes.filter(node => node?.type === 'box' && node.value).length;
                 if (!spreads[geometry.spreadIndex]) {
                     spreads[geometry.spreadIndex] = { index: geometry.spreadIndex, left: [], right: [] };
                 }
@@ -93,10 +96,13 @@ class BookPaginationModule extends BaseModule {
                     pageLine: geometry.pageLine,
                     fontPx: layout.fontPx,
                     lineHeightPx: layout.lineHeightPx,
-                    fontStyle: layout.fontStyle
+                    fontStyle: layout.fontStyle,
+                    blockWordStart: blockWordCursor
                 });
+                blockWordCursor += lineWordCount;
                 cursorLine += 1;
             });
+            cursorLine += layout.bottomSpaceLines;
         });
 
         return spreads.filter(Boolean);
@@ -109,6 +115,8 @@ class BookPaginationModule extends BaseModule {
         const typography = this.metrics.typography;
         const role = block.role || block.metadata?.role || (type === 'heading' ? 'chapter-heading' : 'body');
         const isHeading = type === 'heading' || role === 'chapter-heading' || role === 'section-heading';
+        const topSpaceLines = role === 'chapter-heading' ? 2 : role === 'section-heading' || block.addTopSpace || block.metadata?.addTopSpace ? 1 : 0;
+        const bottomSpaceLines = role === 'chapter-heading' || role === 'section-heading' ? 1 : 0;
         const lineHeightPx = Math.max(1, Number(this.metrics.typographyLineHeightPx || 1));
         const fontPx = Math.max(1, Number(this.metrics.bodyFontSizePx || lineHeightPx / 1.5));
         const indent = (isHeading || block.isFirstParagraphInChapter || block.metadata?.isFirstParagraphInChapter || block.addTopSpace)
@@ -123,6 +131,7 @@ class BookPaginationModule extends BaseModule {
             measures,
             fontSize: `${fontPx}px`,
             fontFamily: typography.fontFamily,
+            fontFeatureSettings: '"kern" on, "liga" on, "onum" on, "pnum" on, "dlig" on, "clig" on, "calt" on',
             lineHeightPx,
             lineHeight: lineHeightPx / fontPx
         });
@@ -133,6 +142,8 @@ class BookPaginationModule extends BaseModule {
             fontPx,
             lineHeightPx,
             fontStyle: isHeading ? 'italic' : 'normal',
+            topSpaceLines,
+            bottomSpaceLines,
             lines: this.extractLines(layout, {
                 measures,
                 lineOffsets,