Share the effect from the phong material

This only loads the shader source once instead of 1000 times. Reduces
the time to first frame by a further 30% by massively reducing the
work the main thread has to do at startup. The Qt3DExtras material
classes are convenient but lead to bad practices like this. We should
provide a way to allow them to share the effect easily but still use
the provided materials for their API. Perhaps a new ctor overload that
takes a QEffect pointer would work nicely.

Also fixed some float vs double vs int precision warnings as a drive
by.

Change-Id: I181de8d95841eb88c91c29ef6f45d215da079b98
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

3 files changed, 32 insertions, 21 deletions

diff --git a/tests/manual/bigscene-cpp/entity.cpp b/tests/manual/bigscene-cpp/entity.cpp
index 6cd969777..876a2d171 100644
--- a/tests/manual/bigscene-cpp/entity.cpp
+++ b/tests/manual/bigscene-cpp/entity.cpp
@@ -51,15 +51,21 @@
 #include "entity.h"
 
 #include <Qt3DExtras/QCylinderMesh>
-#include <Qt3DExtras/QPhongMaterial>
+#include <Qt3DRender/QMaterial>
+#include <Qt3DRender/QParameter>
 #include <Qt3DCore/QTransform>
 #include <QMatrix4x4>
 
-Entity::Entity(Qt3DCore::QNode *parent)
+Entity::Entity(Qt3DRender::QEffect *effect, Qt3DCore::QNode *parent)
     : QEntity(parent)
     , m_transform(new Qt3DCore::QTransform())
-    , m_material(new Qt3DExtras::QPhongMaterial())
+    , m_material(new Qt3DRender::QMaterial())
+    , m_diffuseColorParam(new Qt3DRender::QParameter())
 {
+    m_diffuseColorParam->setName(QLatin1String("kd"));
+    m_material->addParameter(m_diffuseColorParam);
+    m_material->setEffect(effect);
+
     addComponent(m_transform);
     addComponent(m_material);
 }
@@ -90,7 +96,7 @@ QVector3D Entity::position() const
 
 QColor Entity::diffuseColor() const
 {
-    return m_material->diffuse();
+    return m_diffuseColorParam->value().value<QColor>();
 }
 
 void Entity::setTheta(float theta)
@@ -129,9 +135,11 @@ void Entity::setPosition(QVector3D position)
 
 void Entity::setDiffuseColor(QColor diffuseColor)
 {
-    if (m_material->diffuse() == diffuseColor)
+    if (m_diffuseColorParam->value().value<QColor>() == diffuseColor)
         return;
 
-    m_material->setDiffuse(diffuseColor);
+    m_diffuseColorParam->setValue(QVariant::fromValue(diffuseColor));
+    const bool wasBlocked = blockNotifications(true);
     emit diffuseColorChanged(diffuseColor);
+    blockNotifications(wasBlocked);
 }
diff --git a/tests/manual/bigscene-cpp/entity.h b/tests/manual/bigscene-cpp/entity.h
index 6c2310a35..656511cdc 100644
--- a/tests/manual/bigscene-cpp/entity.h
+++ b/tests/manual/bigscene-cpp/entity.h
@@ -62,12 +62,10 @@ class QTransform;
 }
 
 namespace Qt3DRender {
+class QEffect;
 class QGeometryRenderer;
-}
-
-namespace Qt3DExtras {
-class QCylinderMesh;
-class QPhongMaterial;
+class QMaterial;
+class QParameter;
 }
 
 QT_END_NAMESPACE
@@ -81,7 +79,7 @@ class Entity : public Qt3DCore::QEntity
     Q_PROPERTY(QColor diffuseColor READ diffuseColor WRITE setDiffuseColor NOTIFY diffuseColorChanged)
 
 public:
-    Entity(Qt3DCore::QNode *parent = 0);
+    Entity(Qt3DRender::QEffect *effect, Qt3DCore::QNode *parent = 0);
 
     float theta() const;
     float phi() const;
@@ -105,7 +103,8 @@ private:
 
 private:
     Qt3DCore::QTransform *m_transform;
-    Qt3DExtras::QPhongMaterial *m_material;
+    Qt3DRender::QMaterial *m_material;
+    Qt3DRender::QParameter *m_diffuseColorParam;
     float m_theta;
     float m_phi;
     QVector3D m_position;
diff --git a/tests/manual/bigscene-cpp/main.cpp b/tests/manual/bigscene-cpp/main.cpp
index cf893e051..ef296e04d 100644
--- a/tests/manual/bigscene-cpp/main.cpp
+++ b/tests/manual/bigscene-cpp/main.cpp
@@ -88,6 +88,10 @@ int main(int ac, char **av)
     mesh->setRadius(2.5f);
     mesh->setLength(5.0f);
 
+    // Material
+    auto phongMaterial = new Qt3DExtras::QPhongMaterial(root);
+    auto effect = phongMaterial->effect();
+
     // Camera
     QCamera *cameraEntity = view.camera();
     cameraEntity->lens()->setPerspectiveProjection(45.0f, 16.0f/9.0f, 0.1f, 1000.0f);
@@ -99,18 +103,20 @@ int main(int ac, char **av)
     Qt3DExtras::QFirstPersonCameraController *camController = new Qt3DExtras::QFirstPersonCameraController(root);
     camController->setCamera(cameraEntity);
 
-    const float radius = 100.0f;
+    const double radius = 100.0;
     const int max = 1000;
-    const float det = 1.0f / max;
+    const double det = 1.0 / max;
 
     // Scene
     for (int i = 0; i < max; i++) {
-        Entity *e = new Entity();
+        Entity *e = new Entity(effect, root);
         e->addComponent(mesh);
-        const float angle = M_PI * 2.0f * i * det * 10.;
+        const double angle = M_PI * 2.0 * double(i) * det * 10.;
 
-        e->setDiffuseColor(QColor(qFabs(qCos(angle)) * 255, 204, 75));
-        e->setPosition(QVector3D(radius * qCos(angle), -200.* i * det, radius * qSin(angle)));
+        e->setDiffuseColor(QColor(int(qFabs(qCos(angle)) * 255.0), 204, 75));
+        e->setPosition(QVector3D(float(radius * qCos(angle)),
+                                 float(-200.0 * i * det),
+                                 float(radius * qSin(angle))));
         e->setTheta(30.0f * i);
         e->setPhi(45.0f * i);
 
@@ -127,8 +133,6 @@ int main(int ac, char **av)
         animZ->setEndValue(QVariant::fromValue((i + 1) * 380.0f));
         animZ->setLoopCount(-1);
         animZ->start();
-
-        e->setParent(root);
     }
 
     view.setRootEntity(root);