diff --git a/examples/EffectDropShadow.cpp b/examples/EffectDropShadow.cpp
index ede4c56a..446c0974 100644
--- a/examples/EffectDropShadow.cpp
+++ b/examples/EffectDropShadow.cpp
@@ -103,7 +103,7 @@ struct UserExample : tvgexam::Example
         scene2->push(tvg::SceneEffect::DropShadow, 65, 143, 222, (int)(255.0f * progress), 135.0, 10.0, 3.0, 100);
 
         scene3->push(tvg::SceneEffect::ClearAll);
-        scene3->push(tvg::SceneEffect::DropShadow, 0, 0, 0, 125, (double)(360.0f * progress), 20.0, 3.0, 100);
+        scene3->push(tvg::SceneEffect::DropShadow, 0, 0, 0, 125, (double)(360.0f * progress), 20.0, 0.0, 100);
 
         canvas->update();
 
diff --git a/src/renderer/gl_engine/tvgGlEffect.cpp b/src/renderer/gl_engine/tvgGlEffect.cpp
index 1e8d5046..12ee22ba 100644
--- a/src/renderer/gl_engine/tvgGlEffect.cpp
+++ b/src/renderer/gl_engine/tvgGlEffect.cpp
@@ -141,7 +141,7 @@ void GlEffect::update(RenderEffectDropShadow* effect, const Matrix& transform)
     dropShadow->offset[1] = offset.y;
     dropShadow->extend = 2 * std::max(sigma * scale + std::abs(offset.x), sigma * scale + std::abs(offset.y));
     effect->rd = dropShadow;
-    effect->valid = (dropShadow->extend > 0);
+    effect->valid = (dropShadow->extend >= 0);
 }
 
 
diff --git a/src/renderer/gl_engine/tvgGlRenderTask.cpp b/src/renderer/gl_engine/tvgGlRenderTask.cpp
index 9cd206e2..b6a505e1 100644
--- a/src/renderer/gl_engine/tvgGlRenderTask.cpp
+++ b/src/renderer/gl_engine/tvgGlRenderTask.cpp
@@ -544,20 +544,23 @@ void GlEffectDropShadowTask::run()
     GL_CHECK(glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST));
     
     GL_CHECK(glDisable(GL_BLEND));
-    // horizontal blur
-    GL_CHECK(glBindFramebuffer(GL_FRAMEBUFFER, mDstCopyFbo0->getResolveFboId()));
-    horzTask->setViewport(vp);
-    horzTask->addBindResource({ 0, dstCopyTexId1, horzSrcTextureLoc });
-    horzTask->run();
-    // vertical blur
-    GL_CHECK(glBindFramebuffer(GL_FRAMEBUFFER, mDstCopyFbo1->getResolveFboId()));
-    vertTask->setViewport(vp);
-    vertTask->addBindResource({ 0, dstCopyTexId0, vertSrcTextureLoc });
-    vertTask->run();
-    // copy original image to intermediate buffer
-    GL_CHECK(glBindFramebuffer(GL_READ_FRAMEBUFFER, mDstFbo->getFboId()));
-    GL_CHECK(glBindFramebuffer(GL_DRAW_FRAMEBUFFER, mDstCopyFbo0->getResolveFboId()));
-    GL_CHECK(glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST));
+    // when sigma is 0, no blur is applied, and the original image is used directly as the shadow.
+    if (!tvg::zero(effect->sigma)) {
+        // horizontal blur
+        GL_CHECK(glBindFramebuffer(GL_FRAMEBUFFER, mDstCopyFbo0->getResolveFboId()));
+        horzTask->setViewport(vp);
+        horzTask->addBindResource({ 0, dstCopyTexId1, horzSrcTextureLoc });
+        horzTask->run();
+        // vertical blur
+        GL_CHECK(glBindFramebuffer(GL_FRAMEBUFFER, mDstCopyFbo1->getResolveFboId()));
+        vertTask->setViewport(vp);
+        vertTask->addBindResource({ 0, dstCopyTexId0, vertSrcTextureLoc });
+        vertTask->run();
+        // copy original image to intermediate buffer
+        GL_CHECK(glBindFramebuffer(GL_READ_FRAMEBUFFER, mDstFbo->getFboId()));
+        GL_CHECK(glBindFramebuffer(GL_DRAW_FRAMEBUFFER, mDstCopyFbo0->getResolveFboId()));
+        GL_CHECK(glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST));
+    }
     // run drop shadow effect
     GL_CHECK(glBindFramebuffer(GL_FRAMEBUFFER, mDstFbo->getFboId()));
     GlRenderTask::run();
diff --git a/src/renderer/wg_engine/tvgWgCompositor.cpp b/src/renderer/wg_engine/tvgWgCompositor.cpp
index c27d827d..65bb8212 100644
--- a/src/renderer/wg_engine/tvgWgCompositor.cpp
+++ b/src/renderer/wg_engine/tvgWgCompositor.cpp
@@ -875,8 +875,9 @@ bool WgCompositor::dropShadow(WgContext& context, WgRenderTarget* dst, const Ren
     auto aabb = compose->aabb;
     auto viewport = compose->rdViewport;
 
-    { // apply blur
-        copyTexture(&targetTemp1, dst, aabb);
+    copyTexture(&targetTemp1, dst, aabb);
+     // when sigma is 0, no blur is applied, and the original image is used directly as the shadow.
+    if (!tvg::zero(params->sigma)) {
         WgRenderTarget* sbuff = &targetTemp1;
         WgRenderTarget* dbuff = &targetTemp0;
         WGPUComputePassDescriptor computePassDesc{ .label = "Compute pass drop shadow blur" };
diff --git a/src/renderer/wg_engine/tvgWgRenderer.cpp b/src/renderer/wg_engine/tvgWgRenderer.cpp
index 12ffa7a9..36cccb7c 100644
--- a/src/renderer/wg_engine/tvgWgRenderer.cpp
+++ b/src/renderer/wg_engine/tvgWgRenderer.cpp
@@ -538,10 +538,10 @@ bool WgRenderer::region(RenderEffect* effect)
     } else if (effect->type == SceneEffect::DropShadow) {
         auto dropShadow = (RenderEffectDropShadow*)effect;
         auto renderData = (WgRenderDataEffectParams*)dropShadow->rd;
-        dropShadow->extend.min.x = -(renderData->extend + std::abs(renderData->offset.x));
-        dropShadow->extend.max.x = +(renderData->extend + std::abs(renderData->offset.x));
-        dropShadow->extend.min.y = -(renderData->extend + std::abs(renderData->offset.y));
-        dropShadow->extend.max.y = +(renderData->extend + std::abs(renderData->offset.y));
+        dropShadow->extend.min.x = -std::ceil(renderData->extend + std::abs(renderData->offset.x));
+        dropShadow->extend.min.y = -std::ceil(renderData->extend + std::abs(renderData->offset.y));
+        dropShadow->extend.max.x = +std::floor(renderData->extend + std::abs(renderData->offset.x));
+        dropShadow->extend.max.y = +std::floor(renderData->extend + std::abs(renderData->offset.y));
         return true;
     }
     return false;
diff --git a/src/renderer/wg_engine/tvgWgShaderTypes.cpp b/src/renderer/wg_engine/tvgWgShaderTypes.cpp
index 71f51c6b..05f67e15 100644
--- a/src/renderer/wg_engine/tvgWgShaderTypes.cpp
+++ b/src/renderer/wg_engine/tvgWgShaderTypes.cpp
@@ -247,7 +247,7 @@ bool WgShaderTypeEffectParams::update(RenderEffectDropShadow* dropShadow, const
     params[9] = offset.y;
     extend = params[2] * 2; // kernel
 
-    dropShadow->valid = (extend > 0);
+    dropShadow->valid = (extend >= 0);
     return dropShadow->valid;
 }