Track the glVertexAttribPointer and only update it if it's changed

This removes a lot of unnecessary GL state changes resulting in an
18% performance boost on desktop and 5% on SGX for the 25920 3x3
solid rectangle test case.

Reviewed-By: Samuel

3 files changed, 61 insertions, 34 deletions

diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index ff096c2..f8f0347 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -580,19 +580,19 @@ void QGL2PaintEngineExPrivate::transferMode(EngineMode newMode)
     }
 
     if (newMode == TextDrawingMode) {
-        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, vertexCoordinateArray.data());
-        glVertexAttribPointer(QT_TEXTURE_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, textureCoordinateArray.data());
+        setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, (GLfloat*)vertexCoordinateArray.data());
+        setVertexAttributePointer(QT_TEXTURE_COORDS_ATTR, (GLfloat*)textureCoordinateArray.data());
     }
 
     if (newMode == ImageDrawingMode) {
-        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, staticVertexCoordinateArray);
-        glVertexAttribPointer(QT_TEXTURE_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, staticTextureCoordinateArray);
+        setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, staticVertexCoordinateArray);
+        setVertexAttributePointer(QT_TEXTURE_COORDS_ATTR, staticTextureCoordinateArray);
     }
 
     if (newMode == ImageArrayDrawingMode) {
-        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, vertexCoordinateArray.data());
-        glVertexAttribPointer(QT_TEXTURE_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, textureCoordinateArray.data());
-        glVertexAttribPointer(QT_OPACITY_ATTR, 1, GL_FLOAT, GL_FALSE, 0, opacityArray.data());
+        setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, (GLfloat*)vertexCoordinateArray.data());
+        setVertexAttributePointer(QT_TEXTURE_COORDS_ATTR, (GLfloat*)textureCoordinateArray.data());
+        setVertexAttributePointer(QT_OPACITY_ATTR, (GLfloat*)opacityArray.data());
     }
 
     // This needs to change when we implement high-quality anti-aliasing...
@@ -707,9 +707,9 @@ void QGL2PaintEngineExPrivate::fill(const QVectorPath& path)
             prepareForDraw(currentBrush.isOpaque());
 #ifdef QT_OPENGL_CACHE_AS_VBOS
             glBindBuffer(GL_ARRAY_BUFFER, cache->vbo);
-            glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, false, 0, 0);
+            setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, 0);
 #else
-            glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, false, 0, cache->vertices);
+            setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, cache->vertices);
 #endif
             glDrawArrays(cache->primitiveType, 0, cache->vertexCount);
 
@@ -829,7 +829,7 @@ void QGL2PaintEngineExPrivate::fillStencilWithVertexArray(const float *data,
         glStencilMask(GL_STENCIL_HIGH_BIT);
 #if 0
         glStencilOp(GL_KEEP, GL_KEEP, GL_INVERT); // Simply invert the stencil bit
-        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, data);
+        setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, data);
         glDrawArrays(GL_TRIANGLE_STRIP, 0, count);
 #else
 
@@ -840,7 +840,7 @@ void QGL2PaintEngineExPrivate::fillStencilWithVertexArray(const float *data,
         } else {
             glStencilFunc(GL_ALWAYS, GL_STENCIL_HIGH_BIT, 0xff);
         }
-        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, data);
+        setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, data);
         glDrawArrays(GL_TRIANGLE_STRIP, 0, count);
 #endif
     }
@@ -954,15 +954,8 @@ bool QGL2PaintEngineExPrivate::prepareForDraw(bool srcPixelsAreOpaque)
 
 void QGL2PaintEngineExPrivate::composite(const QGLRect& boundingRect)
 {
-    // Setup a vertex array for the bounding rect:
-    GLfloat rectVerts[] = {
-        boundingRect.left, boundingRect.top,
-        boundingRect.left, boundingRect.bottom,
-        boundingRect.right, boundingRect.bottom,
-        boundingRect.right, boundingRect.top
-    };
-
-    glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, rectVerts);
+    setCoords(staticVertexCoordinateArray, boundingRect);
+    setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, staticVertexCoordinateArray);
     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 }
 
@@ -971,7 +964,7 @@ void QGL2PaintEngineExPrivate::drawVertexArrays(const float *data, int *stops, i
                                                 GLenum primitive)
 {
     // Now setup the pointer to the vertex array:
-    glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, data);
+    setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, (GLfloat*)data);
 
     int previousStop = 0;
     for (int i=0; i<stopCount; ++i) {
@@ -1070,7 +1063,7 @@ void QGL2PaintEngineExPrivate::stroke(const QVectorPath &path, const QPen &pen)
 
     if (opaque) {
         prepareForDraw(opaque);
-        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, false, 0, stroker.vertices());
+        setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, stroker.vertices());
         glDrawArrays(GL_TRIANGLE_STRIP, 0, stroker.vertexCount() / 2);
 
 //         QBrush b(Qt::green);
@@ -1291,9 +1284,6 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(const QPointF &p, QFontEngineGly
     GLfloat dx = 1.0 / cache->width();
     GLfloat dy = 1.0 / cache->height();
 
-    QGLPoint *oldVertexCoordinateDataPtr = vertexCoordinateArray.data();
-    QGLPoint *oldTextureCoordinateDataPtr = textureCoordinateArray.data();
-
     vertexCoordinateArray.clear();
     textureCoordinateArray.clear();
 
@@ -1306,10 +1296,8 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(const QPointF &p, QFontEngineGly
         textureCoordinateArray.addRect(QRectF(c.x*dx, c.y*dy, c.w * dx, c.h * dy));
     }
 
-    if (vertexCoordinateArray.data() != oldVertexCoordinateDataPtr)
-        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, vertexCoordinateArray.data());
-    if (textureCoordinateArray.data() != oldTextureCoordinateDataPtr)
-        glVertexAttribPointer(QT_TEXTURE_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, textureCoordinateArray.data());
+    setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, (GLfloat*)vertexCoordinateArray.data());
+    setVertexAttributePointer(QT_TEXTURE_COORDS_ATTR, (GLfloat*)textureCoordinateArray.data());
 
     if (addOffset) {
         addOffset = false;
@@ -1641,6 +1629,8 @@ void QGL2PaintEngineEx::ensureActive()
         d->shaderManager->setDirty();
         d->ctx->d_func()->syncGlState();
         setState(state());
+        for (int i = 0; i < 3; ++i)
+            d->vertexAttribPointers[i] = (GLfloat*)-1; // Assume the pointers are clobbered
     }
 }
 
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
index eaae187..f745196 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
@@ -196,6 +196,9 @@ public:
     void drawPixmaps(const QDrawPixmaps::Data *drawingData, int dataCount, const QPixmap &pixmap, QDrawPixmaps::DrawingHints hints);
     void drawCachedGlyphs(const QPointF &p, QFontEngineGlyphCache::Type glyphType, const QTextItemInt &ti);
 
+    // Calls glVertexAttributePointer if the pointer has changed
+    inline void setVertexAttributePointer(unsigned int arrayIndex, const GLfloat *pointer);
+
     // draws whatever is in the vertex array:
     void drawVertexArrays(const float *data, int *stops, int stopCount, GLenum primitive);
     void drawVertexArrays(QGL2PEXVertexArray &vertexArray, GLenum primitive) {
@@ -230,6 +233,7 @@ public:
     void regenerateClip();
     void systemStateChanged();
 
+
     static QGLEngineShaderManager* shaderManagerForEngine(QGL2PaintEngineEx *engine) { return engine->d_func()->shaderManager; }
     static QGL2PaintEngineExPrivate *getData(QGL2PaintEngineEx *engine) { return engine->d_func(); }
     static void cleanupVectorPath(QPaintEngineEx *engine, void *data);
@@ -291,8 +295,24 @@ public:
 
     QSet<QVectorPath::CacheEntry *> pathCaches;
     QVector<GLuint> unusedVBOSToClean;
+
+    const GLfloat *vertexAttribPointers[3];
 };
 
+
+void QGL2PaintEngineExPrivate::setVertexAttributePointer(unsigned int arrayIndex, const GLfloat *pointer)
+{
+    Q_ASSERT(arrayIndex < 3);
+    if (pointer == vertexAttribPointers[arrayIndex])
+        return;
+
+    vertexAttribPointers[arrayIndex] = pointer;
+    if (arrayIndex == QT_OPACITY_ATTR)
+        glVertexAttribPointer(arrayIndex, 1, GL_FLOAT, GL_FALSE, 0, pointer);
+    else
+        glVertexAttribPointer(arrayIndex, 2, GL_FLOAT, GL_FALSE, 0, pointer);
+}
+
 QT_END_NAMESPACE
 
 #endif
diff --git a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
index 047876f..4034448 100644
--- a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
+++ b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
@@ -127,11 +127,28 @@ void QGLTextureGlyphCache::resizeTextureData(int width, int height)
 
     glViewport(0, 0, oldWidth, oldHeight);
 
-    float vertexCoordinateArray[] = { -1, -1, 1, -1, 1, 1, -1, 1 };
-    float textureCoordinateArray[] = { 0, 0, 1, 0, 1, 1, 0, 1 };
-
-    glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, vertexCoordinateArray);
-    glVertexAttribPointer(QT_TEXTURE_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, textureCoordinateArray);
+    GLfloat* vertexCoordinateArray = pex->staticVertexCoordinateArray;
+    vertexCoordinateArray[0] = -1.0f;
+    vertexCoordinateArray[1] = -1.0f;
+    vertexCoordinateArray[2] =  1.0f;
+    vertexCoordinateArray[3] = -1.0f;
+    vertexCoordinateArray[4] =  1.0f;
+    vertexCoordinateArray[5] =  1.0f;
+    vertexCoordinateArray[6] = -1.0f;
+    vertexCoordinateArray[7] =  1.0f;
+
+    GLfloat* textureCoordinateArray = pex->staticTextureCoordinateArray;
+    textureCoordinateArray[0] = 0.0f;
+    textureCoordinateArray[1] = 0.0f;
+    textureCoordinateArray[2] = 1.0f;
+    textureCoordinateArray[3] = 0.0f;
+    textureCoordinateArray[4] = 1.0f;
+    textureCoordinateArray[5] = 1.0f;
+    textureCoordinateArray[6] = 0.0f;
+    textureCoordinateArray[7] = 1.0f;
+
+    pex->setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, vertexCoordinateArray);
+    pex->setVertexAttributePointer(QT_TEXTURE_COORDS_ATTR, textureCoordinateArray);
 
     pex->shaderManager->useBlitProgram();
     pex->shaderManager->blitProgram()->setUniformValue("imageTexture", QT_IMAGE_TEXTURE_UNIT);