Fix: GPU drag behavior

Author: AlexIchenskiy

package.json

@@ -109,4 +109,4 @@
       "main"
     ]
   }
-}
+}

src/renderer/webgl/shaders/edge/edge.frag

@@ -17,6 +17,8 @@ in float vShadowSize;
 in vec2 vShadowOffset;
 flat in int vEdgeType;
 
+uniform bool uSimpleMode;
+
 out vec4 fragColor;
 
 float sdSegment(vec2 p, vec2 a, vec2 b) {
@@ -89,32 +91,44 @@ float sdArrow(vec2 p, vec2 tip, vec2 dir, float size) {
 }
 
 void main() {
-  float cutoff = vHalfWidth + vShadowSize + length(vShadowOffset) + vArrowSize + 2.0;
+  if (uSimpleMode && vEdgeType == 0) {
+    fragColor = vColor;
+    return;
+  }
 
+  // Edge SDF: type-based dispatch (always needed).
   float dist;
-  float shadowDist;
-  vec2 shadowPos = vWorldPos - vShadowOffset;
-
   if (vEdgeType == 0) {
     dist = sdSegment(vWorldPos, vStart, vEnd);
-    shadowDist = sdSegment(shadowPos, vStart, vEnd);
   } else if (vEdgeType == 1) {
     dist = sdBezier(vWorldPos, vStart, vControl, vEnd);
-    shadowDist = sdBezier(shadowPos, vStart, vControl, vEnd);
   } else {
     dist = abs(length(vWorldPos - vControl) - vLoopbackRadius);
-    shadowDist = abs(length(shadowPos - vControl) - vLoopbackRadius);
   }
 
-  float arrowDist = sdArrow(vWorldPos, vArrowTip, vArrowDir, vArrowSize);
-  float shadowArrowDist = sdArrow(shadowPos, vArrowTip, vArrowDir, vArrowSize);
-
   float edgeSdf = dist - vHalfWidth;
-  float combinedSdf = min(edgeSdf, arrowDist);
-  float shadowCombined = min(shadowDist - vHalfWidth, shadowArrowDist);
+  float combinedSdf = edgeSdf;
+
+  if (vArrowSize > 0.0) {
+    float arrowDist = sdArrow(vWorldPos, vArrowTip, vArrowDir, vArrowSize);
+    combinedSdf = min(edgeSdf, arrowDist);
+  }
 
   float shadowAlpha = 0.0;
   if (vShadowSize > 0.0) {
+    vec2 shadowPos = vWorldPos - vShadowOffset;
+    float shadowDist;
+    if (vEdgeType == 0) {
+      shadowDist = sdSegment(shadowPos, vStart, vEnd);
+    } else if (vEdgeType == 1) {
+      shadowDist = sdBezier(shadowPos, vStart, vControl, vEnd);
+    } else {
+      shadowDist = abs(length(shadowPos - vControl) - vLoopbackRadius);
+    }
+    float shadowArrowDist = vArrowSize > 0.0
+      ? sdArrow(shadowPos, vArrowTip, vArrowDir, vArrowSize)
+      : 1.0e6;
+    float shadowCombined = min(shadowDist - vHalfWidth, shadowArrowDist);
     float t = max(shadowCombined, 0.0) / vShadowSize;
     shadowAlpha = exp(-t * t * 1.5) * 0.5 * vShadowColor.a;
   }
@@ -128,6 +142,10 @@ void main() {
 
   if (finalAlpha < 0.001) discard;
 
-  vec3 finalRGB = (edgeColor.rgb * edgeColor.a + vShadowColor.rgb * shadowAlpha * (1.0 - edgeColor.a)) / finalAlpha;
-  fragColor = vec4(finalRGB, finalAlpha);
+  if (shadowAlpha > 0.0) {
+    vec3 finalRGB = (edgeColor.rgb * edgeColor.a + vShadowColor.rgb * shadowAlpha * (1.0 - edgeColor.a)) / finalAlpha;
+    fragColor = vec4(finalRGB, finalAlpha);
+  } else {
+    fragColor = edgeColor;
+  }
 }

src/renderer/webgl/shaders/edge/edge.vert

@@ -44,7 +44,8 @@ void main() {
   vStart = aStart;
   vEnd = aEnd;
   vControl = aControl;
-  vHalfWidth = aWidth * 0.5;
+  float effectiveWidth = max(aWidth, 1.0 / uScale);
+  vHalfWidth = effectiveWidth * 0.5;
   vLoopbackRadius = aLoopbackRadius;
   vArrowSize = aArrowSize;
   vArrowTip = aArrowTip;

src/renderer/webgl/shaders/node/node.frag

@@ -107,18 +107,21 @@ float shapeSDF(vec2 p, float r, int shapeType) {
 }
 
 void main() {
+  // Body SDF - always needed.
   float dist = shapeSDF(vUV, vNodeRadius, vShapeType);
-  float shadowDist = shapeSDF(vUV - vShadowOffset, vNodeRadius, vShapeType);
 
+  float aa = 0.02 * vNodeRadius;
+  float nodeAlpha = 1.0 - smoothstep(-aa, 0.0, dist);
+
+  // Shadow SDF - skip entirely when no shadow. Avoids a second full shapeSDF() call
+  // (which is a cascade of ifs) and the exp() per fragment.
   float shadowAlpha = 0.0;
   if (vShadowBlur > 0.0) {
+    float shadowDist = shapeSDF(vUV - vShadowOffset, vNodeRadius, vShapeType);
     float t = max(shadowDist, 0.0) / vShadowBlur;
     shadowAlpha = exp(-t * t * 1.5) * 0.5 * vShadowColor.a;
   }
 
-  float aa = 0.02 * vNodeRadius;
-  float nodeAlpha = 1.0 - smoothstep(-aa, 0.0, dist);
-
   vec4 fillColor = vColor;
   if (vImageAspect > 0.0 && dist < 0.0) {
     vec2 uv01 = (vUV / vNodeRadius) * 0.5 + 0.5;
@@ -134,9 +137,14 @@ void main() {
     }
   }
 
-  float borderDist = shapeSDF(vUV, vBorderThreshold, vShapeType);
-  float borderMix = smoothstep(-aa, aa, borderDist);
-  vec4 nodeColor = mix(fillColor, vBorderColor, borderMix);
+  vec4 nodeColor;
+  if (vBorderThreshold < vNodeRadius) {
+    float borderDist = shapeSDF(vUV, vBorderThreshold, vShapeType);
+    float borderMix = smoothstep(-aa, aa, borderDist);
+    nodeColor = mix(fillColor, vBorderColor, borderMix);
+  } else {
+    nodeColor = fillColor;
+  }
   nodeColor.a *= nodeAlpha;
 
   float finalAlpha = nodeColor.a + shadowAlpha * (1.0 - nodeColor.a);
@@ -145,6 +153,10 @@ void main() {
     discard;
   }
 
-  vec3 finalRGB = (nodeColor.rgb * nodeColor.a + vShadowColor.rgb * shadowAlpha * (1.0 - nodeColor.a)) / finalAlpha;
-  fragColor = vec4(finalRGB, finalAlpha);
+  if (shadowAlpha > 0.0) {
+    vec3 finalRGB = (nodeColor.rgb * nodeColor.a + vShadowColor.rgb * shadowAlpha * (1.0 - nodeColor.a)) / finalAlpha;
+    fragColor = vec4(finalRGB, finalAlpha);
+  } else {
+    fragColor = nodeColor;
+  }
 }