From 586cae3ac69c0c667fbf8a954edbd399f620a717 Mon Sep 17 00:00:00 2001
From: Romain Guy <romainguy@google.com>
Date: Fri, 13 Jul 2012 15:28:31 -0700
Subject: Improve rendering speed by disabling scissor tests

This change improves execution of display lists, particularly on
tiled renderers. The goal is to disable the scissor test as
often as possible. Drawing commands are rarely clipped by View
bounds so most of them can be drawn without doing a scissor test.

The speed improvements scale with the number of views and drawing
commands.

Change-Id: Ibd9b5e051a3e4300562463805acc4fd744ba6266
---
 libs/hwui/OpenGLRenderer.cpp | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

(limited to 'libs/hwui/OpenGLRenderer.cpp')

diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 933d01232271..cbf7b02dcddf 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -157,7 +157,6 @@ void OpenGLRenderer::setViewport(int width, int height) {
     mFirstSnapshot->viewport.set(0, 0, width, height);
 
     glDisable(GL_DITHER);
-    glEnable(GL_SCISSOR_TEST);
     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
 
     glEnableVertexAttribArray(Program::kBindingPosition);
@@ -181,6 +180,7 @@ int OpenGLRenderer::prepareDirty(float left, float top, float right, float botto
     syncState();
 
     if (!opaque) {
+        mCaches.enableScissor();
         mCaches.setScissor(left, mSnapshot->height - bottom, right - left, bottom - top);
         glClear(GL_COLOR_BUFFER_BIT);
         return DrawGlInfo::kStatusDrew;
@@ -250,7 +250,7 @@ void OpenGLRenderer::resume() {
     glViewport(0, 0, snapshot->viewport.getWidth(), snapshot->viewport.getHeight());
     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
 
-    glEnable(GL_SCISSOR_TEST);
+    mCaches.enableScissor();
     mCaches.resetScissor();
     dirtyClip();
 
@@ -651,6 +651,7 @@ bool OpenGLRenderer::createFboLayer(Layer* layer, Rect& bounds, sp<Snapshot> sna
 #endif
 
     // Clear the FBO, expand the clear region by 1 to get nice bilinear filtering
+    mCaches.enableScissor();
     mCaches.setScissor(clip.left - 1.0f, bounds.getHeight() - clip.bottom - 1.0f,
             clip.getWidth() + 2.0f, clip.getHeight() + 2.0f);
     glClear(GL_COLOR_BUFFER_BIT);
@@ -981,7 +982,7 @@ void OpenGLRenderer::clearLayerRegions() {
         // The list contains bounds that have already been clipped
         // against their initial clip rect, and the current clip
         // is likely different so we need to disable clipping here
-        glDisable(GL_SCISSOR_TEST);
+        mCaches.disableScissor();
 
         Vertex mesh[count * 6];
         Vertex* vertex = mesh;
@@ -1008,8 +1009,6 @@ void OpenGLRenderer::clearLayerRegions() {
         setupDrawVertices(&mesh[0].position[0]);
 
         glDrawArrays(GL_TRIANGLES, 0, count * 6);
-
-        glEnable(GL_SCISSOR_TEST);
     } else {
         for (uint32_t i = 0; i < count; i++) {
             delete mLayers.itemAt(i);
@@ -1088,7 +1087,12 @@ bool OpenGLRenderer::quickReject(float left, float top, float right, float botto
     Rect clipRect(*mSnapshot->clipRect);
     clipRect.snapToPixelBoundaries();
 
-    return !clipRect.intersects(r);
+    bool rejected = !clipRect.intersects(r);
+    if (!isDeferred() && !rejected) {
+        mCaches.setScissorEnabled(!clipRect.contains(r));
+    }
+
+    return rejected;
 }
 
 bool OpenGLRenderer::clipRect(float left, float top, float right, float bottom, SkRegion::Op op) {
-- 
cgit v1.2.3-59-g8ed1b