wg_engine: Viewport support

[issues 1479: Viewport](#1479)

Supports viewport settings and rectangular clip path.
Scissors cliping used as a way to clip viewport

src/renderer/wg_engine/tvgWgRenderData.h

@@ -86,6 +86,7 @@ struct WgRenderSettings
 struct WgRenderDataPaint
 {
     WgBindGroupPaint bindGroupPaint{};
+    RenderRegion viewport{};
     float opacity{};
 
     virtual ~WgRenderDataPaint() {};

src/renderer/wg_engine/tvgWgRenderTarget.cpp

@@ -30,6 +30,7 @@
  {
     release(context);
     // store target storage size
+    this->samples = samples;
     width = w * samples;
     height = h * samples;
     workgroupsCountX = (width  + WG_COMPUTE_WORKGROUP_SIZE_X - 1) / WG_COMPUTE_WORKGROUP_SIZE_X; // workgroup size x == 8
@@ -100,6 +101,8 @@ void WgRenderStorage::renderPicture(WgContext& context, WgRenderDataPicture* ren
     assert(renderData);
     assert(mRenderPassEncoder);
     uint8_t blend = (uint8_t)blendType;
+    auto& vp = renderData->viewport;
+    wgpuRenderPassEncoderSetScissorRect(mRenderPassEncoder, vp.x * samples, vp.y * samples, vp.w * samples, vp.h * samples);
     wgpuRenderPassEncoderSetStencilReference(mRenderPassEncoder, 0);
     mPipelines->image[blend].use(mRenderPassEncoder, mBindGroupCanvas, renderData->bindGroupPaint, renderData->bindGroupPicture);
     renderData->meshData.drawImage(context, mRenderPassEncoder);
@@ -112,7 +115,8 @@ void WgRenderStorage::drawShape(WgContext& context, WgRenderDataShape* renderDat
     assert(mRenderPassEncoder);
     assert(renderData->meshGroupShapes.meshes.count == renderData->meshGroupShapesBBox.meshes.count);
     if (renderData->renderSettingsShape.skip) return;
-    // draw shape geometry
+    auto& vp = renderData->viewport;
+    wgpuRenderPassEncoderSetScissorRect(mRenderPassEncoder, vp.x * samples, vp.y * samples, vp.w * samples, vp.h * samples);
     wgpuRenderPassEncoderSetStencilReference(mRenderPassEncoder, 0);
     // setup fill rule
     if (renderData->fillRule == FillRule::Winding)
@@ -141,6 +145,8 @@ void WgRenderStorage::drawStroke(WgContext& context, WgRenderDataShape* renderDa
     assert(mRenderPassEncoder);
     assert(renderData->meshGroupStrokes.meshes.count == renderData->meshGroupStrokesBBox.meshes.count);
     if (renderData->renderSettingsStroke.skip) return;
+    auto& vp = renderData->viewport;
+    wgpuRenderPassEncoderSetScissorRect(mRenderPassEncoder, vp.x * samples, vp.y * samples, vp.w * samples, vp.h * samples);
     // draw stroke geometry
     uint8_t blend = (uint8_t)blendType;
     // draw strokes to stencil (first pass)

src/renderer/wg_engine/tvgWgRenderTarget.h

@@ -38,6 +38,7 @@ public:
     WGPUTextureView texViewStencil{};
     WgBindGroupTextureStorageRgba bindGroupTexStorageRgba;
     WgBindGroupTextureStorageBgra bindGroupTexStorageBgra;
+    uint32_t samples{};
     uint32_t width{};
     uint32_t height{};
     uint32_t workgroupsCountX{};

src/renderer/wg_engine/tvgWgRenderer.cpp

@@ -113,6 +113,7 @@ RenderData WgRenderer::prepare(const RenderShape& rshape, RenderData data, const
     }
 
     // setup fill settings
+    renderDataShape->viewport = mViewport;
     renderDataShape->opacity = opacity;
     renderDataShape->renderSettingsShape.update(mContext, rshape.fill, rshape.color, flags);
     if (rshape.stroke)
@@ -136,6 +137,7 @@ RenderData WgRenderer::prepare(Surface* surface, const RenderMesh* mesh, RenderD
         renderDataPicture = new WgRenderDataPicture();
 
     // update paint settings
+    renderDataPicture->viewport = mViewport;
     renderDataPicture->opacity = opacity;
     if (flags & (RenderUpdateFlag::Transform | RenderUpdateFlag::Blend)) {
         WgShaderTypeMat4x4f modelMat(transform);
@@ -261,17 +263,18 @@ RenderRegion WgRenderer::region(TVG_UNUSED RenderData data)
 
 
 RenderRegion WgRenderer::viewport() {
-    return { 0, 0, INT32_MAX, INT32_MAX };
+    return mViewport;
 }
 
 
-bool WgRenderer::viewport(TVG_UNUSED const RenderRegion& vp)
+bool WgRenderer::viewport(const RenderRegion& vp)
 {
+    mViewport = vp;
     return true;
 }
 
 
-bool WgRenderer::blend(TVG_UNUSED BlendMethod method)
+bool WgRenderer::blend(BlendMethod method)
 {
     mBlendMethod = method;
     return false;

src/renderer/wg_engine/tvgWgRenderer.h

@@ -80,6 +80,7 @@ private:
     WgContext mContext;
     WgPipelines mPipelines;
     Surface mTargetSurface;
+    RenderRegion mViewport{};
 
     BlendMethod mBlendMethod{};    // current blend method