wg_engine: introduced global vertexbuffer mempool & ++thread safety

Manage the global buffer memory for vertex and indexed vertex buffers,
increase the memory size incrementally twice by default and reduce
the default buffer size, which is not suitable for typical scenarios.

This could reduce the a bit stack memory usage and improve
the portability across systems where has the stack memory
limitation and potentially gaining performance enhancement
by avoiding brutal stack memory usage at the many function calls.

added the internal functions:

- WgVertexBuffer* mpoolReqVertexBuffer(float scale = 1.0f);
- WgIndexedVertexBuffer* mpoolReqIndexedVertexBuffer(float scale = 1.0f);
- void mpoolRetVertexBuffer(WgVertexBuffer* buffer);
- void mpoolRetIndexedVertexBuffer(WgIndexedVertexBuffer* buffer);

issue: https://github.com/thorvg/thorvg/issues/3159

cross/wasm32.txt

@@ -12,7 +12,7 @@ exe_suffix = 'js'
 
 [built-in options]
 cpp_args = ['-Wshift-negative-value', '-flto', '-Oz', '-fno-exceptions']
-cpp_link_args = ['-Wshift-negative-value', '-flto', '-Oz', '-fno-exceptions', '--bind', '-sWASM=1', '-sALLOW_MEMORY_GROWTH=1', '-sEXPORT_ES6=1', '-sFORCE_FILESYSTEM=1', '-sMODULARIZE=1', '-sEXPORTED_RUNTIME_METHODS=FS', '-sUSE_WEBGPU=1', '-sSTACK_SIZE=2MB', '-sMAX_WEBGL_VERSION=2', '-sFULL_ES3']
+cpp_link_args = ['-Wshift-negative-value', '-flto', '-Oz', '-fno-exceptions', '--bind', '-sWASM=1', '-sALLOW_MEMORY_GROWTH=1', '-sEXPORT_ES6=1', '-sFORCE_FILESYSTEM=1', '-sMODULARIZE=1', '-sEXPORTED_RUNTIME_METHODS=FS', '-sUSE_WEBGPU=1', '-sMAX_WEBGL_VERSION=2', '-sFULL_ES3']
 
 [host_machine]
 system = 'emscripten'

cross/wasm32_wg.txt

@@ -12,7 +12,7 @@ exe_suffix = 'js'
 
 [built-in options]
 cpp_args = ['-Wshift-negative-value', '-flto', '-Oz', '-fno-exceptions']
-cpp_link_args = ['-Wshift-negative-value', '-flto', '-Oz', '-fno-exceptions', '--bind', '-sWASM=1', '-sALLOW_MEMORY_GROWTH=1', '-sEXPORT_ES6=1', '-sFORCE_FILESYSTEM=1', '-sMODULARIZE=1', '-sEXPORTED_RUNTIME_METHODS=FS', '-sUSE_WEBGPU=1', '-sSTACK_SIZE=2MB']
+cpp_link_args = ['-Wshift-negative-value', '-flto', '-Oz', '-fno-exceptions', '--bind', '-sWASM=1', '-sALLOW_MEMORY_GROWTH=1', '-sEXPORT_ES6=1', '-sFORCE_FILESYSTEM=1', '-sMODULARIZE=1', '-sEXPORTED_RUNTIME_METHODS=FS', '-sUSE_WEBGPU=1']
 
 [host_machine]
 system = 'emscripten'

src/renderer/wg_engine/meson.build

@@ -12,6 +12,7 @@ source_file = [
     'tvgWgBindGroups.cpp',
     'tvgWgCommon.cpp',
     'tvgWgCompositor.cpp',
+    'tvgWgGeometry.cpp',
     'tvgWgPipelines.cpp',
     'tvgWgRenderData.cpp',
     'tvgWgRenderer.cpp',

src/renderer/wg_engine/tvgWgGeometry.cpp

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2025 the ThorVG project. All rights reserved.
+
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "tvgWgGeometry.h"
+
+
+/************************************************************************/
+/* Internal Class Implementation                                        */
+/************************************************************************/
+
+static WgGeometryBufferPool _pool;
+
+/************************************************************************/
+/* External Class Implementation                                        */
+/************************************************************************/
+
+WgVertexBuffer* WgGeometryBufferPool::reqVertexBuffer(float scale)
+{
+    ARRAY_FOREACH(p, vbuffers) {
+        if ((*p)->count == 0) {
+            (*p)->scale = scale;
+            return (*p);
+        }
+    }
+    vbuffers.push(new WgVertexBuffer(scale));
+    return vbuffers.last();
+}
+
+void WgGeometryBufferPool::retVertexBuffer(WgVertexBuffer* buffer)
+{
+    buffer->reset(1.0f);
+}
+
+WgIndexedVertexBuffer* WgGeometryBufferPool::reqIndexedVertexBuffer(float scale)
+{
+    ARRAY_FOREACH(p, ibuffers) {
+        if ((*p)->vcount == 0) {
+            (*p)->scale = scale;
+            return (*p);
+        }
+    }
+    ibuffers.push(new WgIndexedVertexBuffer(this, scale));
+    return ibuffers.last();
+}
+
+void WgGeometryBufferPool::retIndexedVertexBuffer(WgIndexedVertexBuffer* buffer)
+{
+    buffer->reset(1.0f);
+}
+
+
+WgGeometryBufferPool* WgGeometryBufferPool::instance()
+{
+    /* TODO: These could be easily addressed per threads. i.e _pool[thread_cnt]; */
+    return &_pool;
+}
+
+
+WgGeometryBufferPool::~WgGeometryBufferPool()
+{
+    ARRAY_FOREACH(p, vbuffers) delete(*p);
+    ARRAY_FOREACH(p, ibuffers) delete(*p);
+}

src/renderer/wg_engine/tvgWgGeometry.h

@@ -29,57 +29,93 @@
 
 
 // default size of vertex and index buffers
-#define WG_POINTS_COUNT 32768
+#define WG_DEFAULT_BUFFER_SIZE 2048
+
+struct WgVertexBuffer;
+struct WgIndexedVertexBuffer;
+
+struct WgGeometryBufferPool
+{
+private:
+    Array<WgVertexBuffer*> vbuffers;
+    Array<WgIndexedVertexBuffer*> ibuffers;
+
+public:
+    ~WgGeometryBufferPool();
+
+    WgVertexBuffer* reqVertexBuffer(float scale = 1.0f);
+    WgIndexedVertexBuffer* reqIndexedVertexBuffer(float scale = 1.0f);
+    void retVertexBuffer(WgVertexBuffer* buffer);
+    void retIndexedVertexBuffer(WgIndexedVertexBuffer* buffer);
+
+    static WgGeometryBufferPool* instance();  //return the shared buffer pool
+};
+
 
 // simple vertex buffer
 struct WgVertexBuffer
 {
-    Point vbuff[WG_POINTS_COUNT]; // vertex buffer
+    Point* data;           // vertex buffer
-    float vdist[WG_POINTS_COUNT]; // distance to previous point
+    struct Distance {
-    float vleng[WG_POINTS_COUNT]; // distance to the first point through all previous points
+        float interval;    // distance to previous point
-    size_t vcount{};
+        float length;      // distance to the first point through all previous points
-    bool closed{};
+    } *dist;
-    float tscale = 1.0f; // tesselation scale
+    uint32_t count = 0;
+    uint32_t reserved = WG_DEFAULT_BUFFER_SIZE;
+    float scale;           // tesselation scale
+    bool closed = false;
 
     // callback for external process of polyline
     using onPolylineFn = std::function<void(const WgVertexBuffer& buff)>;
 
+    WgVertexBuffer(float scale = 1.0f) : scale(scale)
+    {
+        data = (Point*)malloc(sizeof(Point) * reserved);
+        dist = (Distance*)malloc(sizeof(Distance) * reserved);
+    }
+
+    ~WgVertexBuffer()
+    {
+        free(data);
+        free(dist);
+    }
+
     // reset buffer
     void reset(float scale)
     {
-        vcount = 0;
+        count = 0;
         closed = false;
-        tscale = scale;
+        this->scale = scale;
     }
 
     // get the last point with optional index offset from the end
     Point last(size_t offset = 0) const
     {
-        return vbuff[vcount - offset - 1];
+        return data[count - offset - 1];
     }
 
     // get the last distance with optional index offset from the end
     float lastDist(size_t offset = 0) const
     {
-        return vdist[vcount - offset - 1];
+        return dist[count - offset - 1].interval;
     }
 
     // get total length
     float total() const
     {
-        return (vcount == 0) ? 0.0f : vleng[vcount-1];
+        return (count == 0) ? 0.0f : dist[count-1].length;
     }
 
     // get next vertex index by length using binary search
     size_t getIndexByLength(float len) const
     {
-        if (vcount <= 1) return 0;
+        if (count <= 1) return 0;
         size_t left = 0;
-        size_t right = vcount - 1;
+        size_t right = count - 1;
         while (left <= right) {
             size_t mid = left + (right - left) / 2;
-            if (vleng[mid] == len) return mid;
+            if (dist[mid].length == len) return mid;
-            else if (vleng[mid] < len) left = mid + 1;
+            else if (dist[mid].length < len) left = mid + 1;
             else right = mid - 1;
         }
         return right + 1;
@@ -88,23 +124,23 @@ struct WgVertexBuffer
     // get min and max values of the buffer
     void getMinMax(Point& pmin, Point& pmax) const
     {
-        if (vcount == 0) return;
+        if (count == 0) return;
-        pmax = pmin = vbuff[0];
+        pmax = pmin = data[0];
-        for (size_t i = 1; i < vcount; i++) {
+        for (size_t i = 1; i < count; i++) {
-            pmin = min(pmin, vbuff[i]);
+            pmin = min(pmin, data[i]);
-            pmax = max(pmax, vbuff[i]);
+            pmax = max(pmax, data[i]);
         }
     }
 
     // update points distancess to the prev point and total length
     void updateDistances()
     {
-        if (vcount == 0) return;
+        if (count == 0) return;
-        vdist[0] = 0.0f;
+        dist[0].interval = 0.0f;
-        vleng[0] = 0.0f;
+        dist[0].length = 0.0f;
-        for (size_t i = 1; i < vcount; i++) {
+        for (size_t i = 1; i < count; i++) {
-            vdist[i] = length(vbuff[i-1] - vbuff[i]);
+            dist[i].interval = tvg::length(data[i-1] - data[i]);
-            vleng[i] = vleng[i-1] + vdist[i];
+            dist[i].length = dist[i-1].length + dist[i].interval;
         }
     }
 
@@ -112,23 +148,29 @@ struct WgVertexBuffer
     void close()
     {
         // check if last point is not to close to the first point
-        if (!tvg::zero(length2(vbuff[0] - last())))
+        if (!tvg::zero(length2(data[0] - last()))) {
-            append(vbuff[0]);
+            append(data[0]);
+        }
         closed = true;
     }
 
     // append point
     void append(const Point& p)
     {
-        vbuff[vcount] = p;
+        if (count >= reserved) {
-        vcount++;
+            reserved *= 2;
+            data = (Point*) realloc(data, reserved * sizeof(Point));
+            dist = (Distance*) realloc(dist, reserved * sizeof(Distance));
+        }
+        data[count++] = p;
     }
 
     // append source vertex buffer in index range from start to end (end not included)
     void appendRange(const WgVertexBuffer& buff, size_t start_index, size_t end_index)
     {
-        for (size_t i = start_index; i < end_index; i++)
+        for (size_t i = start_index; i < end_index; i++) {
-            append(buff.vbuff[i]);
+            append(buff.data[i]);
+        }
     }
 
     // append circle (list of triangles)
@@ -136,7 +178,7 @@ struct WgVertexBuffer
     {
         // get approx circle length
         float clen = 2.0f * radius * MATH_PI;
-        size_t nsegs = std::max((uint32_t)(clen * tscale / 8), 16U);
+        size_t nsegs = std::max((uint32_t)(clen * scale / 8), 16U);
         // append circle^
         Point prev { std::sin(0.0f) * radius, std::cos(0.0f) * radius };
         for (size_t i = 1; i <= nsegs; i++) {
@@ -153,19 +195,20 @@ struct WgVertexBuffer
     void appendCubic(const Point& v0, const Point& v1, const Point& v2, const Point& v3)
     {
         // get approx cubic length
-        float clen = (length(v0 - v1) + length(v1 - v2) + length(v2 - v3));
+        float clen = (tvg::length(v0 - v1) + tvg::length(v1 - v2) + tvg::length(v2 - v3));
-        size_t nsegs = std::max((uint32_t)(clen * tscale / 16), 16U);
+        size_t nsegs = std::max((uint32_t)(clen * scale / 16), 16U);
         // append cubic
         Bezier bezier{v0, v1, v2, v3};
-        for (size_t i = 1; i <= nsegs; i++)
+        for (size_t i = 1; i <= nsegs; i++) {
             append(bezier.at((float)i / nsegs));
+        }
     }
 
     // decode path with callback for external prcesses
     void decodePath(const RenderShape& rshape, bool update_dist, onPolylineFn onPolyline, bool trim = false)
     {
         // decode path
-        reset(tscale);
+        reset(scale);
 
         PathCommand *cmds, *trimmedCmds = nullptr;
         Point *pts, *trimmedPts = nullptr;
@@ -193,8 +236,8 @@ struct WgVertexBuffer
             if (cmd == PathCommand::MoveTo) {
                 // after path decoding we need to update distances and total length
                 if (update_dist) updateDistances();
-                if ((onPolyline) && (vcount > 0)) onPolyline(*this);
+                if ((onPolyline) && (count > 0)) onPolyline(*this);
-                reset(tscale);
+                reset(scale);
                 append(pts[pntIndex]);
                 pntIndex++;
             } else if (cmd == PathCommand::LineTo) {
@@ -203,20 +246,18 @@ struct WgVertexBuffer
             } else if (cmd == PathCommand::Close) {
                 close();
                 // proceed path if close command is not the last command and next command is LineTo or CubicTo
-                if (i + 1 < cmdCnt &&
+                if (i + 1 < cmdCnt && (cmds[i + 1] == PathCommand::LineTo || cmds[i + 1] == PathCommand::CubicTo)) {
-                    (cmds[i + 1] == PathCommand::LineTo ||
-                     cmds[i + 1] == PathCommand::CubicTo)) {
                     // proceed current path
                     if (update_dist) updateDistances();
-                    if ((vcount > 0) && (onPolyline)) onPolyline(*this);
+                    if ((count > 0) && (onPolyline)) onPolyline(*this);
                     // append closing point of current path as a first point of the new path
                     Point last_pt = last();
-                    reset(tscale);
+                    reset(scale);
                     append(last_pt);
                 }
             } else if (cmd == PathCommand::CubicTo) {
-                // append tesselated cubic spline with tscale param
+                // append tesselated cubic spline with scale param
-                appendCubic(vbuff[vcount - 1], pts[pntIndex + 0], pts[pntIndex + 1], pts[pntIndex + 2]);
+                appendCubic(data[count - 1], pts[pntIndex + 0], pts[pntIndex + 1], pts[pntIndex + 2]);
                 pntIndex += 3;
             }
         }
@@ -226,28 +267,58 @@ struct WgVertexBuffer
 
         // after path decoding we need to update distances and total length
         if (update_dist) updateDistances();
-        if ((vcount > 0) && (onPolyline)) onPolyline(*this);
+        if ((count > 0) && (onPolyline)) onPolyline(*this);
-        reset(tscale);
+        reset(scale);
     }
 };
 
-// simple indexed vertex buffer
+
-struct WgVertexBufferInd
+struct WgIndexedVertexBuffer
 {
-    Point vbuff[WG_POINTS_COUNT*16];
+    Point* vbuff;
-    Point tbuff[WG_POINTS_COUNT*16];
+    uint32_t* ibuff;
-    uint32_t ibuff[WG_POINTS_COUNT*16];
+    uint32_t vcount = 0, icount = 0;
-    size_t vcount = 0;
+    size_t vreserved = WG_DEFAULT_BUFFER_SIZE;
-    size_t icount = 0;
+    size_t ireserved = WG_DEFAULT_BUFFER_SIZE * 2;
-    float tscale = 1.0f;
+    WgGeometryBufferPool* pool;
-    // intermediate buffer for stroke dashing
+    WgVertexBuffer* dashed;   // intermediate buffer for stroke dashing
-    WgVertexBuffer dashed;
+    float scale;
+
+    WgIndexedVertexBuffer(WgGeometryBufferPool* pool, float scale = 1.0f) : pool(pool), scale(scale)
+    {
+        vbuff = (Point*)malloc(sizeof(Point) * vreserved);
+        ibuff = (uint32_t*)malloc(sizeof(uint32_t) * ireserved);
+        dashed = pool->reqVertexBuffer();
+    }
+
+    ~WgIndexedVertexBuffer()
+    {
+        pool->retVertexBuffer(dashed);
+        free(vbuff);
+        free(ibuff);
+    }
 
     // reset buffer
     void reset(float scale)
     {
         icount = vcount = 0;
-        tscale = scale;
+        this->scale = scale;
+    }
+
+    void growIndex(size_t grow)
+    {
+        if (icount + grow >= ireserved) {
+            ireserved *= 2;
+            ibuff = (uint32_t*) realloc(ibuff, ireserved * sizeof(uint32_t));
+        }
+    }
+
+    void growVertex(size_t grow)
+    {
+        if (vcount + grow >= vreserved) {
+            vreserved *= 2;
+            vbuff = (Point*) realloc(vbuff, vreserved * sizeof(Point));
+        }
     }
 
     // get min and max values of the buffer
@@ -264,19 +335,20 @@ struct WgVertexBufferInd
     // append quad - two triangles formed from four points
     void appendQuad(const Point& p0, const Point& p1, const Point& p2, const Point& p3)
     {
-        // append vertexes
+        growVertex(4);
         vbuff[vcount+0] = p0;
         vbuff[vcount+1] = p1;
         vbuff[vcount+2] = p2;
         vbuff[vcount+3] = p3;
-        // append indexes
+
+        growIndex(6);
         ibuff[icount+0] = vcount + 0;
         ibuff[icount+1] = vcount + 1;
         ibuff[icount+2] = vcount + 2;
         ibuff[icount+3] = vcount + 1;
         ibuff[icount+4] = vcount + 3;
         ibuff[icount+5] = vcount + 2;
-        // update buffer
+
         vcount += 4;
         icount += 6;
     }
@@ -285,9 +357,9 @@ struct WgVertexBufferInd
     void appendStrokesDashed(const WgVertexBuffer& buff, const RenderStroke* rstroke)
     {
         // dashed buffer
-        dashed.reset(tscale);
+        dashed->reset(scale);
         // ignore single points polyline
-        if (buff.vcount < 2) return;
+        if (buff.count < 2) return;
         const float* dashPattern = rstroke->dashPattern;
         size_t dashCnt = rstroke->dashCnt;
         // starting state
@@ -295,8 +367,9 @@ struct WgVertexBufferInd
         float len_total = dashPattern[index_dash];
         // get dashes length
         float dashes_lenth{};
-        for (uint32_t i = 0; i < dashCnt * (dashCnt % 2 + 1); i++)
+        for (uint32_t i = 0; i < dashCnt * (dashCnt % 2 + 1); i++) {
             dashes_lenth += dashPattern[i % dashCnt];
+        }
         if (dashes_lenth == 0) return;
         // normalize dash offset
         float dashOffset = rstroke->dashOffset;
@@ -311,51 +384,54 @@ struct WgVertexBufferInd
         }
         len_total -= dashOffset;
         // iterate by polyline points
-        for (uint32_t i = 0; i < buff.vcount - 1; i++) {
+        for (uint32_t i = 0; i < buff.count - 1; i++) {
             // append current polyline point
-            if (!gap) dashed.append(buff.vbuff[i]);
+            if (!gap) dashed->append(buff.data[i]);
             // move inside polyline segment
-            while(len_total < buff.vdist[i+1]) {
+            while(len_total < buff.dist[i+1].interval) {
                 // get current point
-                dashed.append(tvg::lerp(buff.vbuff[i], buff.vbuff[i+1], len_total / buff.vdist[i+1]));
+                dashed->append(tvg::lerp(buff.data[i], buff.data[i+1], len_total / buff.dist[i+1].interval));
                 // update current state
                 index_dash = (index_dash + 1) % dashCnt;
                 len_total += dashPattern[index_dash];
                 // preceed stroke if dash
                 if (!gap) {
-                    dashed.updateDistances();
+                    dashed->updateDistances();
-                    appendStrokes(dashed, rstroke);
+                    appendStrokes(*dashed, rstroke);
-                    dashed.reset(tscale);
+                    dashed->reset(scale);
                 }
                 gap = !gap;
             }
             // update current subline length
-            len_total -= buff.vdist[i+1];
+            len_total -= buff.dist[i+1].interval;
         }
         // draw last subline
         if (!gap) {
-            dashed.append(buff.last());
+            dashed->append(buff.last());
-            dashed.updateDistances();
+            dashed->updateDistances();
-            appendStrokes(dashed, rstroke);
+            appendStrokes(*dashed, rstroke);
         }
     }
 
     // append buffer with optional offset
     void appendBuffer(const WgVertexBuffer& buff, Point offset = Point{0.0f, 0.0f})
     {
-        for (uint32_t i = 0; i < buff.vcount; i++ ) {
+        growVertex(buff.count);
-            vbuff[vcount + i] = buff.vbuff[i] + offset;
+        growIndex(buff.count);
+
+        for (uint32_t i = 0; i < buff.count; i++) {
+            vbuff[vcount + i] = buff.data[i] + offset;
             ibuff[icount + i] = vcount + i;
         }
-        vcount += buff.vcount;
+        vcount += buff.count;
-        icount += buff.vcount;
+        icount += buff.count;
     };
 
     void appendLine(const Point& v0, const Point& v1, float dist, float halfWidth)
     {
         if(tvg::zero(dist)) return;
         Point sub = v1 - v0;
-        Point nrm = { +sub.y / dist * halfWidth, -sub.x / dist * halfWidth };
+        Point nrm = {sub.y / dist * halfWidth, -sub.x / dist * halfWidth};
         appendQuad(v0 - nrm, v0 + nrm, v1 - nrm, v1 + nrm);
     }
 
@@ -364,8 +440,8 @@ struct WgVertexBufferInd
         if(tvg::zero(dist1) || tvg::zero(dist2)) return;
         Point sub1 = v1 - v0;
         Point sub2 = v2 - v1;
-        Point nrm1 { +sub1.y / dist1 * halfWidth, -sub1.x / dist1 * halfWidth };
+        Point nrm1 {sub1.y / dist1 * halfWidth, -sub1.x / dist1 * halfWidth};
-        Point nrm2 { +sub2.y / dist2 * halfWidth, -sub2.x / dist2 * halfWidth };
+        Point nrm2 {sub2.y / dist2 * halfWidth, -sub2.x / dist2 * halfWidth};
         appendQuad(v1 - nrm1, v1 + nrm1, v1 - nrm2, v1 + nrm2);
     }
 
@@ -398,7 +474,7 @@ struct WgVertexBufferInd
         if(tvg::zero(dist)) return;
         Point sub = v1 - v0;
         Point offset = sub / dist * halfWidth;
-        Point nrm = { +offset.y, -offset.x };
+        Point nrm = {+offset.y, -offset.x};
         appendQuad(v1 - nrm, v1 + nrm, v1 + offset - nrm, v1 + offset + nrm);
     }
 
@@ -406,16 +482,18 @@ struct WgVertexBufferInd
     {
         assert(rstroke);
         // empty buffer gueard
-        if (buff.vcount < 2) return;
+        if (buff.count < 2) return;
+
         float halfWidth = rstroke->width * 0.5f;
 
         // append core lines
-        for (size_t i = 1; i < buff.vcount; i++)
+        for (size_t i = 1; i < buff.count; i++) {
-            appendLine(buff.vbuff[i-1], buff.vbuff[i], buff.vdist[i], halfWidth);
+            appendLine(buff.data[i-1], buff.data[i], buff.dist[i].interval, halfWidth);
+        }
 
         // append caps (square)
         if ((rstroke->cap == StrokeCap::Square) && !buff.closed) {
-            appendSquare(buff.vbuff[1], buff.vbuff[0], buff.vdist[1], halfWidth);
+            appendSquare(buff.data[1], buff.data[0], buff.dist[1].interval, halfWidth);
             appendSquare(buff.last(1), buff.last(0), buff.lastDist(0), halfWidth);
         }
 
@@ -423,19 +501,19 @@ struct WgVertexBufferInd
         if ((rstroke->join == StrokeJoin::Round) || (rstroke->cap == StrokeCap::Round)) {
             // create mesh for circle
             WgVertexBuffer circle;
-            circle.reset(buff.tscale);
+            circle.reset(buff.scale);
             circle.appendCircle(halfWidth);
             // append caps (round)
             if (rstroke->cap == StrokeCap::Round) {
-                appendBuffer(circle, buff.vbuff[0]);
+                appendBuffer(circle, buff.data[0]);
                 // append ending cap if polyline is not closed
-                if (!buff.closed) 
+                if (!buff.closed) appendBuffer(circle, buff.last());
-                    appendBuffer(circle, buff.last());
             }
             // append joints (round)
             if (rstroke->join == StrokeJoin::Round) {
-                for (size_t i = 1; i < buff.vcount - 1; i++)
+                for (size_t i = 1; i < buff.count - 1; i++) {
-                    appendBuffer(circle, buff.vbuff[i]);
+                    appendBuffer(circle, buff.data[i]);
+                }
                 if (buff.closed) appendBuffer(circle, buff.last());
             }
         }
@@ -443,22 +521,24 @@ struct WgVertexBufferInd
         // append closed endings
         if (buff.closed) {
             // close by bevel
-            if (rstroke->join == StrokeJoin::Bevel)
+            if (rstroke->join == StrokeJoin::Bevel) {
-                appendBevel(buff.last(1), buff.vbuff[0], buff.vbuff[1], buff.lastDist(0), buff.vdist[1], halfWidth);
+                appendBevel(buff.last(1), buff.data[0], buff.data[1], buff.lastDist(0), buff.dist[1].interval, halfWidth);
             // close by mitter
-            else if (rstroke->join == StrokeJoin::Miter) {
+            } else if (rstroke->join == StrokeJoin::Miter) {
-                appendMiter(buff.last(1), buff.vbuff[0], buff.vbuff[1], buff.lastDist(0), buff.vdist[1], halfWidth, rstroke->miterlimit);
+                appendMiter(buff.last(1), buff.data[0], buff.data[1], buff.lastDist(0), buff.dist[1].interval, halfWidth, rstroke->miterlimit);
             }
         }
 
         // append joints (bevel)
         if (rstroke->join == StrokeJoin::Bevel) {
-            for (size_t i = 1; i < buff.vcount - 1; i++)
+            for (size_t i = 1; i < buff.count - 1; i++) {
-                appendBevel(buff.vbuff[i-1], buff.vbuff[i], buff.vbuff[i+1], buff.vdist[i], buff.vdist[i+1], halfWidth);
+                appendBevel(buff.data[i-1], buff.data[i], buff.data[i+1], buff.dist[i].interval, buff.dist[i+1].interval, halfWidth);
+            }
         // append joints (mitter)
         } else if (rstroke->join == StrokeJoin::Miter) {
-            for (size_t i = 1; i < buff.vcount - 1; i++)
+            for (size_t i = 1; i < buff.count - 1; i++) {
-                appendMiter(buff.vbuff[i-1], buff.vbuff[i], buff.vbuff[i+1], buff.vdist[i], buff.vdist[i+1], halfWidth, rstroke->miterlimit);
+                appendMiter(buff.data[i-1], buff.data[i], buff.data[i+1], buff.dist[i].interval, buff.dist[i+1].interval, halfWidth, rstroke->miterlimit);
+            }
         }
     }
 };

src/renderer/wg_engine/tvgWgRenderData.cpp

@@ -57,30 +57,21 @@ void WgMeshData::drawImage(WgContext& context, WGPURenderPassEncoder renderPassE
 
 void WgMeshData::update(WgContext& context, const WgVertexBuffer& vertexBuffer)
 {
-    assert(vertexBuffer.vcount > 2);
+    assert(vertexBuffer.count > 2);
-    vertexCount = vertexBuffer.vcount;
+    vertexCount = vertexBuffer.count;
-    indexCount = (vertexBuffer.vcount - 2) * 3;
+    indexCount = (vertexBuffer.count - 2) * 3;
-    // buffer position data create and write
+    context.allocateBufferVertex(bufferPosition, (float*)vertexBuffer.data, vertexCount * sizeof(float) * 2);
-    context.allocateBufferVertex(bufferPosition, (float *)&vertexBuffer.vbuff, vertexCount * sizeof(float) * 2);
-    // buffer index data create and write
     context.allocateBufferIndexFan(vertexCount);
 }
 
 
-void WgMeshData::update(WgContext& context, const WgVertexBufferInd& vertexBufferInd)
+void WgMeshData::update(WgContext& context, const WgIndexedVertexBuffer& vertexBufferInd)
 {
     assert(vertexBufferInd.vcount > 2);
     vertexCount = vertexBufferInd.vcount;
     indexCount = vertexBufferInd.icount;
-    // buffer position data create and write
+    if (vertexCount > 0) context.allocateBufferVertex(bufferPosition, (float*)vertexBufferInd.vbuff, vertexCount * sizeof(float) * 2);
-    if (vertexCount > 0)
+    if (indexCount > 0) context.allocateBufferIndex(bufferIndex, vertexBufferInd.ibuff, indexCount * sizeof(uint32_t));
-        context.allocateBufferVertex(bufferPosition, (float *)&vertexBufferInd.vbuff, vertexCount * sizeof(float) * 2);
-    // buffer tex coords data create and write
-    if (vertexCount > 0)
-        context.allocateBufferVertex(bufferTexCoord, (float *)&vertexBufferInd.tbuff, vertexCount * sizeof(float) * 2);
-    // buffer index data create and write
-    if (indexCount > 0)
-        context.allocateBufferIndex(bufferIndex, vertexBufferInd.ibuff, indexCount * sizeof(uint32_t));
 };
 
 
@@ -88,10 +79,7 @@ void WgMeshData::bbox(WgContext& context, const Point pmin, const Point pmax)
 {
     vertexCount = 4;
     indexCount = 6;
-    const float data[] = {
+    const float data[] = {pmin.x, pmin.y, pmax.x, pmin.y, pmax.x, pmax.y, pmin.x, pmax.y};
-        pmin.x, pmin.y, pmax.x, pmin.y,
-        pmax.x, pmax.y, pmin.x, pmax.y
-    };
     context.allocateBufferVertex(bufferPosition, data, sizeof(data));
     context.allocateBufferIndexFan(vertexCount);
 }
@@ -101,9 +89,9 @@ void WgMeshData::imageBox(WgContext& context, float w, float h)
 {
     vertexCount = 4;
     indexCount = 6;
-    const float vdata[] = { 0.0f, 0.0f,    w, 0.0f,   w,    h,  0.0f, h    };
+    const float vdata[] = {0.0f, 0.0f, w, 0.0f, w, h, 0.0f, h};
-    const float tdata[] = { 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f };
+    const float tdata[] = {0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f};
-    const uint32_t idata[] = { 0, 1, 2, 0, 2, 3 };
+    const uint32_t idata[] = {0, 1, 2, 0, 2, 3};
     context.allocateBufferVertex(bufferPosition, vdata, sizeof(vdata));
     context.allocateBufferVertex(bufferTexCoord, tdata, sizeof(tdata));
     context.allocateBufferIndex(bufferIndex, idata, sizeof(idata));
@@ -114,8 +102,8 @@ void WgMeshData::blitBox(WgContext& context)
 {
     vertexCount = 4;
     indexCount = 6;
-    const float vdata[] = { -1.0f, +1.0f, +1.0f, +1.0f, +1.0f, -1.0f, -1.0f, -1.0f };
+    const float vdata[] = {-1.0f, +1.0f, +1.0f, +1.0f, +1.0f, -1.0f, -1.0f, -1.0f};
-    const float tdata[] = { +0.0f, +0.0f, +1.0f, +0.0f, +1.0f, +1.0f, +0.0f, +1.0f };
+    const float tdata[] = {+0.0f, +0.0f, +1.0f, +0.0f, +1.0f, +1.0f, +0.0f, +1.0f};
     const uint32_t idata[] = { 0, 1, 2, 0, 2, 3 };
     context.allocateBufferVertex(bufferPosition, vdata, sizeof(vdata));
     context.allocateBufferVertex(bufferTexCoord, tdata, sizeof(tdata));
@@ -174,13 +162,13 @@ WgMeshDataPool* WgMeshDataPool::gMeshDataPool = &gMeshDataPoolInstance;
 
 void WgMeshDataGroup::append(WgContext& context, const WgVertexBuffer& vertexBuffer)
 {
-    assert(vertexBuffer.vcount >= 3);
+    assert(vertexBuffer.count >= 3);
     meshes.push(WgMeshDataPool::gMeshDataPool->allocate(context));
     meshes.last()->update(context, vertexBuffer);
 }
 
 
-void WgMeshDataGroup::append(WgContext& context, const WgVertexBufferInd& vertexBufferInd)
+void WgMeshDataGroup::append(WgContext& context, const WgIndexedVertexBuffer& vertexBufferInd)
 {
     assert(vertexBufferInd.vcount >= 3);
     meshes.push(WgMeshDataPool::gMeshDataPool->allocate(context));
@@ -335,7 +323,7 @@ void WgRenderDataPaint::updateClips(tvg::Array<tvg::RenderData> &clips) {
 
 void WgRenderDataShape::appendShape(WgContext& context, const WgVertexBuffer& vertexBuffer)
 {
-    if (vertexBuffer.vcount < 3) return;
+    if (vertexBuffer.count < 3) return;
     Point pmin{}, pmax{};
     vertexBuffer.getMinMax(pmin, pmax);
     meshGroupShapes.append(context, vertexBuffer);
@@ -344,7 +332,7 @@ void WgRenderDataShape::appendShape(WgContext& context, const WgVertexBuffer& ve
 }
 
 
-void WgRenderDataShape::appendStroke(WgContext& context, const WgVertexBufferInd& vertexBufferInd)
+void WgRenderDataShape::appendStroke(WgContext& context, const WgIndexedVertexBuffer& vertexBufferInd)
 {
     if (vertexBufferInd.vcount < 3) return;
     Point pmin{}, pmax{};
@@ -374,7 +362,7 @@ void WgRenderDataShape::updateAABB(const Matrix& tr) {
 }
 
 
-void WgRenderDataShape::updateMeshes(WgContext& context, const RenderShape &rshape, const Matrix& tr)
+void WgRenderDataShape::updateMeshes(WgContext& context, const RenderShape &rshape, const Matrix& tr, WgGeometryBufferPool* pool)
 {
     releaseMeshes(context);
     strokeFirst = rshape.stroke ? rshape.stroke->strokeFirst : false;
@@ -383,24 +371,22 @@ void WgRenderDataShape::updateMeshes(WgContext& context, const RenderShape &rsha
     float scale = std::max(std::min(length(Point{tr.e11 + tr.e12,tr.e21 + tr.e22}), 8.0f), 1.0f);
 
     // path decoded vertex buffer
-    WgVertexBuffer pbuff;
+    auto pbuff = pool->reqVertexBuffer(scale);
-    pbuff.reset(scale);
 
     if (rshape.strokeTrim()) {
-        WgVertexBuffer trimbuff;
+        auto trimbuff =  pool->reqVertexBuffer(scale);
-        trimbuff.reset(scale);
+        pbuff->decodePath(rshape, true, [&](const WgVertexBuffer& path_buff) {
-
-        pbuff.decodePath(rshape, true, [&](const WgVertexBuffer& path_buff) {
             appendShape(context, path_buff);
         });
-        trimbuff.decodePath(rshape, true, [&](const WgVertexBuffer& path_buff) {
+        trimbuff->decodePath(rshape, true, [&](const WgVertexBuffer& path_buff) {
             appendShape(context, path_buff);
-            proceedStrokes(context, rshape.stroke, path_buff);
+            proceedStrokes(context, rshape.stroke, path_buff, pool);
         }, true);
+        pool->retVertexBuffer(trimbuff);
     } else {
-        pbuff.decodePath(rshape, true, [&](const WgVertexBuffer& path_buff) {
+        pbuff->decodePath(rshape, true, [&](const WgVertexBuffer& path_buff) {
             appendShape(context, path_buff);
-            if (rshape.stroke) proceedStrokes(context, rshape.stroke, path_buff);
+            if (rshape.stroke) proceedStrokes(context, rshape.stroke, path_buff, pool);
         });
     }
     // update shapes bbox (with empty path handling)
@@ -409,19 +395,21 @@ void WgRenderDataShape::updateMeshes(WgContext& context, const RenderShape &rsha
         updateAABB(tr);
         meshDataBBox.bbox(context, pMin, pMax);
     } else aabb = {{0, 0}, {0, 0}};
+
+    pool->retVertexBuffer(pbuff);
 }
 
 
-void WgRenderDataShape::proceedStrokes(WgContext& context, const RenderStroke* rstroke, const WgVertexBuffer& buff)
+void WgRenderDataShape::proceedStrokes(WgContext& context, const RenderStroke* rstroke, const WgVertexBuffer& buff, WgGeometryBufferPool* pool)
 {
     assert(rstroke);
-    static WgVertexBufferInd strokesGenerator;
+    auto strokesGenerator = pool->reqIndexedVertexBuffer(buff.scale);
-    strokesGenerator.reset(buff.tscale);
+    if (rstroke->dashPattern) strokesGenerator->appendStrokesDashed(buff, rstroke);
+    else strokesGenerator->appendStrokes(buff, rstroke);
 
-    if (rstroke->dashPattern) strokesGenerator.appendStrokesDashed(buff, rstroke);
+    appendStroke(context, *strokesGenerator);
-    else strokesGenerator.appendStrokes(buff, rstroke);
 
-    appendStroke(context, strokesGenerator);
+    pool->retIndexedVertexBuffer(strokesGenerator);
 }
 
 

src/renderer/wg_engine/tvgWgRenderData.h

@@ -38,7 +38,7 @@ struct WgMeshData {
     void drawImage(WgContext& context, WGPURenderPassEncoder renderPassEncoder);
 
     void update(WgContext& context, const WgVertexBuffer& vertexBuffer);
-    void update(WgContext& context, const WgVertexBufferInd& vertexBufferInd);
+    void update(WgContext& context, const WgIndexedVertexBuffer& vertexBufferInd);
     void bbox(WgContext& context, const Point pmin, const Point pmax);
     void imageBox(WgContext& context, float w, float h);
     void blitBox(WgContext& context);
@@ -60,7 +60,7 @@ struct WgMeshDataGroup {
     Array<WgMeshData*> meshes{};
     
     void append(WgContext& context, const WgVertexBuffer& vertexBuffer);
-    void append(WgContext& context, const WgVertexBufferInd& vertexBufferInd);
+    void append(WgContext& context, const WgIndexedVertexBuffer& vertexBufferInd);
     void append(WgContext& context, const Point pmin, const Point pmax);
     void release(WgContext& context);
 };
@@ -126,11 +126,11 @@ struct WgRenderDataShape: public WgRenderDataPaint
     FillRule fillRule{};
 
     void appendShape(WgContext& context, const WgVertexBuffer& vertexBuffer);
-    void appendStroke(WgContext& context, const WgVertexBufferInd& vertexBufferInd);
+    void appendStroke(WgContext& context, const WgIndexedVertexBuffer& vertexBufferInd);
     void updateBBox(Point pmin, Point pmax);
     void updateAABB(const Matrix& tr);
-    void updateMeshes(WgContext& context, const RenderShape& rshape, const Matrix& tr);
+    void updateMeshes(WgContext& context, const RenderShape& rshape, const Matrix& tr, WgGeometryBufferPool* pool);
-    void proceedStrokes(WgContext& context, const RenderStroke* rstroke, const WgVertexBuffer& buff);
+    void proceedStrokes(WgContext& context, const RenderStroke* rstroke, const WgVertexBuffer& buff, WgGeometryBufferPool* pool);
     void releaseMeshes(WgContext& context);
     void release(WgContext& context) override;
     Type type() override { return Type::Shape; };

src/renderer/wg_engine/tvgWgRenderer.cpp

@@ -147,7 +147,7 @@ RenderData WgRenderer::prepare(const RenderShape& rshape, RenderData data, const
 
     // update geometry
     if ((!data) || (flags & (RenderUpdateFlag::Path | RenderUpdateFlag::Stroke))) {
-        renderDataShape->updateMeshes(mContext, rshape, transform);
+        renderDataShape->updateMeshes(mContext, rshape, transform, mBufferPool.pool);
     }
 
     // update paint settings
@@ -415,6 +415,13 @@ bool WgRenderer::target(WGPUDevice device, WGPUInstance instance, void* target,
 
 WgRenderer::WgRenderer()
 {
+    if (TaskScheduler::onthread()) {
+        TVGLOG("WG_RENDERER", "Running on a non-dominant thread!, Renderer(%p)", this);
+        mBufferPool.pool = new WgGeometryBufferPool;
+        mBufferPool.individual = true;
+    } else {
+        mBufferPool.pool = WgGeometryBufferPool::instance();
+    }
 }
 
 
@@ -422,6 +429,8 @@ WgRenderer::~WgRenderer()
 {
     release();
 
+    if (mBufferPool.individual) delete(mBufferPool.pool);
+
     --rendererCnt;
 
     if (rendererCnt == 0 && initEngineCnt == 0) _termEngine();

src/renderer/wg_engine/tvgWgRenderer.h

@@ -106,6 +106,11 @@ private:
     WGPUTexture targetTexture{}; // external handle
     WGPUSurfaceTexture surfaceTexture{};
     WGPUSurface surface{};  // external handle
+
+    struct {
+        WgGeometryBufferPool* pool;   //private buffer pool
+        bool individual = false;      //buffer-pool sharing policy
+    } mBufferPool;
 };
 
 #endif /* _TVG_WG_RENDERER_H_ */