Initial support for GL_NV_path_renering. Experimental, there are still some issues to resolve, set gyp variable skia_nv_path_rendering=1 or build flag GR_GL_USE_NV_PATH_RENDERING to enable.

http://codereview.appspot.com/6349049/



git-svn-id: http://skia.googlecode.com/svn/trunk/src@4390 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 130 insertions, 0 deletions

diff --git a/gpu/GrStencilAndCoverPathRenderer.cpp b/gpu/GrStencilAndCoverPathRenderer.cpp
new file mode 100644
index 00000000..40d998b6
--- /dev/null
+++ b/gpu/GrStencilAndCoverPathRenderer.cpp
@@ -0,0 +1,130 @@
+
+/*
+ * 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 "GrStencilAndCoverPathRenderer.h"
+#include "GrContext.h"
+#include "GrGpu.h"
+#include "GrPath.h"
+
+GrPathRenderer* GrStencilAndCoverPathRenderer::Create(GrContext* context) {
+    GrAssert(NULL != context);
+    GrAssert(NULL != context->getGpu());
+    if (context->getGpu()->getCaps().fPathStencilingSupport) {
+        return new GrStencilAndCoverPathRenderer(context->getGpu());
+    } else {
+        return NULL;
+    }
+}
+
+GrStencilAndCoverPathRenderer::GrStencilAndCoverPathRenderer(GrGpu* gpu) {
+    GrAssert(gpu->getCaps().fPathStencilingSupport);
+    fGpu = gpu;
+    gpu->ref();
+}
+
+GrStencilAndCoverPathRenderer::~GrStencilAndCoverPathRenderer() {
+    fGpu->unref();
+}
+
+bool GrStencilAndCoverPathRenderer::canDrawPath(const SkPath& path,
+                                                GrPathFill fill,
+                                                const GrDrawTarget* target,
+                                                bool antiAlias) const {
+    return kHairLine_GrPathFill != fill &&
+           !antiAlias && // doesn't do per-path AA, relies on the target having MSAA
+           target->getDrawState().getStencil().isDisabled();
+}
+
+bool GrStencilAndCoverPathRenderer::requiresStencilPass(const SkPath& path,
+                                                        GrPathFill fill,
+                                                        const GrDrawTarget* target) const {
+    return true;
+}
+
+void GrStencilAndCoverPathRenderer::drawPathToStencil(const SkPath& path,
+                                                      GrPathFill fill,
+                                                      GrDrawTarget* target) {
+    GrAssert(kEvenOdd_GrPathFill == fill || kWinding_GrPathFill == fill);
+    SkAutoTUnref<GrPath> p(fGpu->createPath(path));
+    target->stencilPath(p, fill);
+}
+
+bool GrStencilAndCoverPathRenderer::onDrawPath(const SkPath& path,
+                                               GrPathFill fill,
+                                               const GrVec* translate,
+                                               GrDrawTarget* target,
+                                               GrDrawState::StageMask stageMask,
+                                               bool antiAlias){
+    GrAssert(!antiAlias);
+    GrAssert(kHairLine_GrPathFill != fill);
+
+    GrDrawState* drawState = target->drawState();
+    GrAssert(drawState->getStencil().isDisabled());
+
+    SkAutoTUnref<GrPath> p(fGpu->createPath(path));
+    GrDrawState::AutoViewMatrixRestore avmr;
+    if (translate) {
+        avmr.set(drawState);
+        drawState->viewMatrix()->postTranslate(translate->fX, translate->fY);
+    }
+    GrPathFill nonInvertedFill = GrNonInvertedFill(fill);
+    target->stencilPath(p, nonInvertedFill);
+
+    // TODO: Use built in cover operation rather than a rect draw. This will require making our
+    // fragment shaders be able to eat varyings generated by a matrix.
+
+    // fill the path, zero out the stencil
+    GrRect bounds = p->getBounds();
+    GrScalar bloat = drawState->getViewMatrix().getMaxStretch() * GR_ScalarHalf;
+    if (nonInvertedFill == fill) {
+        GR_STATIC_CONST_SAME_STENCIL(kStencilPass,
+            kZero_StencilOp,
+            kZero_StencilOp,
+            kNotEqual_StencilFunc,
+            0xffff,
+            0x0000,
+            0xffff);
+        *drawState->stencil() = kStencilPass;
+    } else {
+        GR_STATIC_CONST_SAME_STENCIL(kInvertedStencilPass,
+            kZero_StencilOp,
+            kZero_StencilOp,
+            kEqual_StencilFunc,
+            0xffff,
+            0x0000,
+            0xffff);
+        GrMatrix vmi;
+        bounds.setLTRB(0, 0,
+                       GrIntToScalar(drawState->getRenderTarget()->width()),
+                       GrIntToScalar(drawState->getRenderTarget()->height()));
+        // mapRect through persp matrix may not be correct
+        if (!drawState->getViewMatrix().hasPerspective() && drawState->getViewInverse(&vmi)) {
+            vmi.mapRect(&bounds);
+            // theoretically could set bloat = 0, instead leave it because of matrix inversion precision.
+        } else {
+            if (stageMask) {
+                if (!drawState->getViewInverse(&vmi)) {
+                    GrPrintf("Could not invert matrix.");
+                    return false;
+                }
+                drawState->preConcatSamplerMatrices(stageMask, vmi);
+            }
+            if (avmr.isSet()) {
+                avmr.set(drawState);
+            }
+            drawState->viewMatrix()->reset();
+            bloat = 0;
+        }
+        *drawState->stencil() = kInvertedStencilPass;
+    }
+    bounds.outset(bloat, bloat);
+    target->drawSimpleRect(bounds, NULL, stageMask);
+    target->drawState()->stencil()->setDisabled();
+    return true;
+}