Avoid re-rendering stencil clip for every draw with reducable clip stack

src/gpu/GrClipMaskManager.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrClipMaskManager.h"
 #include "GrAAConvexPathRenderer.h"
@@ skipping 95 matching lines @@
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // sort out what kind of clip mask needs to be created: alpha, stencil,
 // scissor, or entirely software
 bool GrClipMaskManager::setupClipping(const GrClipData* clipDataIn,
                                       GrDrawState::AutoRestoreEffects* are) {
     fCurrClipMaskType = kNone_ClipMaskType;
 
     ElementList elements(16);
+    int32_t genID;
     InitialState initialState;
     SkIRect clipSpaceIBounds;
     bool requiresAA;
     bool isRect = false;
 
     GrDrawState* drawState = fGpu->drawState();
 
     const GrRenderTarget* rt = drawState->getRenderTarget();
     // GrDrawTarget should have filtered this for us
     SkASSERT(NULL != rt);
 
     bool ignoreClip = !drawState->isClipState() || clipDataIn->fClipStack->isWideOpen();
 
     if (!ignoreClip) {
         SkIRect clipSpaceRTIBounds = SkIRect::MakeWH(rt->width(), rt->height());
         clipSpaceRTIBounds.offset(clipDataIn->fOrigin);
         ReduceClipStack(*clipDataIn->fClipStack,
                         clipSpaceRTIBounds,
                         &elements,
+                        &genID,
                         &initialState,
                         &clipSpaceIBounds,
                         &requiresAA);
         if (elements.isEmpty()) {
             if (kAllIn_InitialState == initialState) {
                 ignoreClip = clipSpaceIBounds == clipSpaceRTIBounds;
                 isRect = true;
             } else {
                 return false;
             }
         }
     }
 
     if (ignoreClip) {
         fGpu->disableScissor();
         this->setGpuStencil();
         return true;
     }
 
 #if GR_AA_CLIP
     // TODO: catch isRect && requiresAA and use clip planes if available rather than a mask.
 
     // If MSAA is enabled we can do everything in the stencil buffer.
     if (0 == rt->numSamples() && requiresAA) {
-        int32_t genID = clipDataIn->fClipStack->getTopmostGenID();
         GrTexture* result = NULL;
 
         if (this->useSWOnlyPath(elements)) {
             // The clip geometry is complex enough that it will be more efficient to create it
             // entirely in software
             result = this->createSoftwareClipMask(genID,
                                                   initialState,
                                                   elements,
                                                   clipSpaceIBounds);
         } else {
@@ skipping 30 matching lines @@
     if (isRect) {
         SkIRect clipRect = clipSpaceIBounds;
         clipRect.offset(-clipDataIn->fOrigin);
         fGpu->enableScissor(clipRect);
         this->setGpuStencil();
         return true;
     }
 
     // use the stencil clip if we can't represent the clip as a rectangle.
     SkIPoint clipSpaceToStencilSpaceOffset = -clipDataIn->fOrigin;
-    this->createStencilClipMask(initialState,
+    this->createStencilClipMask(genID,
+                                initialState,
                                 elements,
                                 clipSpaceIBounds,
                                 clipSpaceToStencilSpaceOffset);
 
     // This must occur after createStencilClipMask. That function may change the scissor. Also, it
     // only guarantees that the stencil mask is correct within the bounds it was passed, so we must
     // use both stencil and scissor test to the bounds for the final draw.
     SkIRect scissorSpaceIBounds(clipSpaceIBounds);
     scissorSpaceIBounds.offset(clipSpaceToStencilSpaceOffset);
     fGpu->enableScissor(scissorSpaceIBounds);
@@ skipping 162 matching lines @@
     desc.fHeight = height;
     desc.fConfig = kAlpha_8_GrPixelConfig;
 
     temp->set(this->getContext(), desc);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Handles caching & allocation (if needed) of a clip alpha-mask texture for both the sw-upload
 // or gpu-rendered cases. Returns true if there is no more work to be done (i.e., we got a cache
 // hit)
-bool GrClipMaskManager::getMaskTexture(int32_t clipStackGenID,
+bool GrClipMaskManager::getMaskTexture(int32_t elementsGenID,
                                        const SkIRect& clipSpaceIBounds,
                                        GrTexture** result,
                                        bool willUpload) {
-    bool cached = fAACache.canReuse(clipStackGenID, clipSpaceIBounds);
+    bool cached = fAACache.canReuse(elementsGenID, clipSpaceIBounds);
     if (!cached) {
 
         // There isn't a suitable entry in the cache so we create a new texture to store the mask.
         // Since we are setting up the cache we know the last lookup was a miss. Free up the
         // currently cached mask so it can be reused.
         fAACache.reset();
 
         GrTextureDesc desc;
         desc.fFlags = willUpload ? kNone_GrTextureFlags : kRenderTarget_GrTextureFlagBit;
         desc.fWidth = clipSpaceIBounds.width();
         desc.fHeight = clipSpaceIBounds.height();
         desc.fConfig = kRGBA_8888_GrPixelConfig;
         if (willUpload || this->getContext()->isConfigRenderable(kAlpha_8_GrPixelConfig, false)) {
             // We would always like A8 but it isn't supported on all platforms
             desc.fConfig = kAlpha_8_GrPixelConfig;
         }
 
-        fAACache.acquireMask(clipStackGenID, desc, clipSpaceIBounds);
+        fAACache.acquireMask(elementsGenID, desc, clipSpaceIBounds);
     }
 
     *result = fAACache.getLastMask();
     return cached;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Create a 8-bit clip mask in alpha
-GrTexture* GrClipMaskManager::createAlphaClipMask(int32_t clipStackGenID,
+GrTexture* GrClipMaskManager::createAlphaClipMask(int32_t elementsGenID,
                                                   InitialState initialState,
                                                   const ElementList& elements,
                                                   const SkIRect& clipSpaceIBounds) {
     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 
     GrTexture* result;
-    if (this->getMaskTexture(clipStackGenID, clipSpaceIBounds, &result, false)) {
+    if (this->getMaskTexture(elementsGenID, clipSpaceIBounds, &result, false)) {
         fCurrClipMaskType = kAlpha_ClipMaskType;
         return result;
     }
 
     if (NULL == result) {
         fAACache.reset();
         return NULL;
     }
 
     // The top-left of the mask corresponds to the top-left corner of the bounds.
@@ skipping 120 matching lines @@
         }
     }
 
     fCurrClipMaskType = kAlpha_ClipMaskType;
     return result;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Create a 1-bit clip mask in the stencil buffer. 'devClipBounds' are in device
 // (as opposed to canvas) coordinates
-bool GrClipMaskManager::createStencilClipMask(InitialState initialState,
+bool GrClipMaskManager::createStencilClipMask(int32_t elementsGenID,
+                                              InitialState initialState,
                                               const ElementList& elements,
                                               const SkIRect& clipSpaceIBounds,
                                               const SkIPoint& clipSpaceToStencilOffset) {
 
     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 
     GrDrawState* drawState = fGpu->drawState();
     SkASSERT(drawState->isClipState());
 
     GrRenderTarget* rt = drawState->getRenderTarget();
     SkASSERT(NULL != rt);
 
     // TODO: dynamically attach a SB when needed.
     GrStencilBuffer* stencilBuffer = rt->getStencilBuffer();
     if (NULL == stencilBuffer) {
         return false;
     }
-    int32_t genID = elements.tail()->getGenID();
 
-    if (stencilBuffer->mustRenderClip(genID, clipSpaceIBounds, clipSpaceToStencilOffset)) {
+    if (stencilBuffer->mustRenderClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset)) {
 
-        stencilBuffer->setLastClip(genID, clipSpaceIBounds, clipSpaceToStencilOffset);
+        stencilBuffer->setLastClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset);
 
         // Set the matrix so that rendered clip elements are transformed from clip to stencil space.
         SkVector translate = {
             SkIntToScalar(clipSpaceToStencilOffset.fX),
             SkIntToScalar(clipSpaceToStencilOffset.fY)
         };
         SkMatrix matrix;
         matrix.setTranslate(translate);
         GrDrawTarget::AutoGeometryAndStatePush agasp(fGpu, GrDrawTarget::kReset_ASRInit, &matrix);
         drawState = fGpu->drawState();
@@ skipping 309 matching lines @@
         } else {
             finished = true;
         }
     }
     if (!twoSided) {
         settings->copyFrontSettingsToBack();
     }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-GrTexture* GrClipMaskManager::createSoftwareClipMask(int32_t clipStackGenID,
+GrTexture* GrClipMaskManager::createSoftwareClipMask(int32_t elementsGenID,
                                                      GrReducedClip::InitialState initialState,
                                                      const GrReducedClip::ElementList& elements,
                                                      const SkIRect& clipSpaceIBounds) {
     SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
 
     GrTexture* result;
-    if (this->getMaskTexture(clipStackGenID, clipSpaceIBounds, &result, true)) {
+    if (this->getMaskTexture(elementsGenID, clipSpaceIBounds, &result, true)) {
         return result;
     }
 
     if (NULL == result) {
         fAACache.reset();
         return NULL;
     }
 
     // The mask texture may be larger than necessary. We round out the clip space bounds and pin
     // the top left corner of the resulting rect to the top left of the texture.
@@ skipping 91 matching lines @@
 
     // TODO: dynamically attach a stencil buffer
     int stencilBits = 0;
     GrStencilBuffer* stencilBuffer =
         drawState.getRenderTarget()->getStencilBuffer();
     if (NULL != stencilBuffer) {
         stencilBits = stencilBuffer->bits();
         this->adjustStencilParams(settings, clipMode, stencilBits);
     }
 }