From 419fa93989450c550f0a19e4eea9fa297a9ef132 Mon Sep 17 00:00:00 2001
From: Sergii Liebodkin <s.lebedkin@gmail.com>
Date: Thu, 13 Jun 2024 16:51:27 +0300
Subject: [PATCH] wg_engine: fix strokes failers and visual atrifacts

Ignoring rezo-width strokes, single point strokes.
Fix visual artifacts in case of mitter joints.
---
 src/renderer/wg_engine/tvgWgGeometry.cpp   | 25 ++++------------------
 src/renderer/wg_engine/tvgWgRenderData.cpp | 23 ++++++++++++--------
 2 files changed, 18 insertions(+), 30 deletions(-)

diff --git a/src/renderer/wg_engine/tvgWgGeometry.cpp b/src/renderer/wg_engine/tvgWgGeometry.cpp
index ea459b92..5365b71c 100644
--- a/src/renderer/wg_engine/tvgWgGeometry.cpp
+++ b/src/renderer/wg_engine/tvgWgGeometry.cpp
@@ -310,11 +310,9 @@ void WgGeometryData::appendStrokeDashed(const WgPolyline* polyline, const Render
     assert(polyline);
     static WgPolyline dashed;
     dashed.clear();
-    // append single point polyline
-    if (polyline->pts.count == 1)
-        appendStroke(polyline, stroke);
+    // ignore singpe points polyline
     // append multy points dashed polyline
-    else if (polyline->pts.count >= 2) {
+    if (polyline->pts.count >= 2) {
         auto& pts = polyline->pts;
         auto& dist = polyline->dist;
        	// starting state
@@ -357,22 +355,7 @@ void WgGeometryData::appendStroke(const WgPolyline* polyline, const RenderStroke
     assert(stroke);
     assert(polyline);
     float wdt = stroke->width / 2;
-    // single point sub-path
-    if (polyline->pts.count == 1) {
-        if (stroke->cap == StrokeCap::Round) {
-            appendCircle(polyline->pts[0], wdt);
-        } else if (stroke->cap == StrokeCap::Butt) {
-            // for zero length sub-paths no stroke is rendered
-        } else if (stroke->cap == StrokeCap::Square) {
-            appendRect(
-                polyline->pts[0] + WgPoint(+wdt, +wdt),
-                polyline->pts[0] + WgPoint(+wdt, -wdt),
-                polyline->pts[0] + WgPoint(-wdt, +wdt),
-                polyline->pts[0] + WgPoint(-wdt, -wdt)
-            );
-        }
-    } else
-    
+
     // single line sub-path
     if (polyline->pts.count == 2) {
         WgPoint v0 = polyline->pts[0];
@@ -474,7 +457,7 @@ void WgGeometryData::appendStroke(const WgPolyline* polyline, const RenderStroke
                     } else if (stroke->join == StrokeJoin::Miter) {
                         WgPoint nrm = (nrm0 + nrm1).normal();
                         float cosine = nrm.dot(nrm0);
-                        if ((cosine != 0.0f) && (abs(cosine) != 1.0f) && (abs(wdt / cosine) <= stroke->miterlimit * 2)) {
+                        if ((cosine != 0.0f) && (abs(cosine) < 1.0f) && (abs(wdt / cosine) <= stroke->miterlimit * 2)) {
                             appendRect(v1 + nrm * (wdt / cosine), v1 + offset0, v1 + offset1, v1);
                             appendRect(v1 - nrm * (wdt / cosine), v1 - offset0, v1 - offset1, v1);
                         } else {
diff --git a/src/renderer/wg_engine/tvgWgRenderData.cpp b/src/renderer/wg_engine/tvgWgRenderData.cpp
index 0da56925..1bdd4650 100644
--- a/src/renderer/wg_engine/tvgWgRenderData.cpp
+++ b/src/renderer/wg_engine/tvgWgRenderData.cpp
@@ -321,16 +321,19 @@ void WgRenderDataShape::updateMeshes(WgContext& context, const WgPolyline* polyl
         updateBBox(pmin, pmax);
     }
     // generate strokes geometry
-    if ((polyline->pts.count >= 1) && rstroke) {
+    if ((polyline->pts.count >= 1) && rstroke && (rstroke->width > 0.0f)) {
         static WgGeometryData geometryData; geometryData.clear();
         static WgPolyline trimmed;
         // trim -> split -> stroke
-        if ((rstroke->dashPattern) && ((rstroke->trim.begin != 0.0f) || (rstroke->trim.end != 1.0f))) {
-            polyline->trim(&trimmed, rstroke->trim.begin, rstroke->trim.end);
+        float trimBegin = rstroke->trim.begin < rstroke->trim.end ? rstroke->trim.begin : rstroke->trim.end;
+        float trimEnd   = rstroke->trim.begin < rstroke->trim.end ? rstroke->trim.end : rstroke->trim.begin;
+        if (trimBegin == trimEnd) return;
+        if ((rstroke->dashPattern) && ((trimBegin != 0.0f) || (trimEnd != 1.0f))) {
+            polyline->trim(&trimmed, trimBegin, trimEnd);
             geometryData.appendStrokeDashed(&trimmed, rstroke);
         } else // trim -> stroke
-        if ((rstroke->trim.begin != 0.0f) || (rstroke->trim.end != 1.0f)) {
-            polyline->trim(&trimmed, rstroke->trim.begin, rstroke->trim.end);
+        if ((trimBegin != 0.0f) || (trimEnd != 1.0f)) {
+            polyline->trim(&trimmed, trimBegin, trimEnd);
             geometryData.appendStroke(&trimmed, rstroke);
         } else // split -> stroke
         if (rstroke->dashPattern) {
@@ -339,10 +342,12 @@ void WgRenderDataShape::updateMeshes(WgContext& context, const WgPolyline* polyl
             geometryData.appendStroke(polyline, rstroke);
         }
         // append render meshes and bboxes
-        WgPoint pmin{}, pmax{};
-        geometryData.positions.getBBox(pmin, pmax);
-        meshGroupStrokes.append(context, &geometryData);
-        meshGroupStrokesBBox.append(context, pmin, pmax);
+        if(geometryData.positions.pts.count >= 3) {
+            WgPoint pmin{}, pmax{};
+            geometryData.positions.getBBox(pmin, pmax);
+            meshGroupStrokes.append(context, &geometryData);
+            meshGroupStrokesBBox.append(context, pmin, pmax);
+        }
     }
 }