Changed the signature of Application::Draw to accept elapsed time. It will be used to update key frames or making the application frame-rate independent. However I think there is some bug somewhere. It takes an eternity for the cube in simple-vertex-shader demo to start rotating. Even when the cube starts rotatiing the performance is quite choppy.

Review URL: http://codereview.chromium.org/551011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@36156 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 26 insertions, 7 deletions

diff --git a/gpu/demos/app_framework/application.cc b/gpu/demos/app_framework/application.cc
index 0ae2cb9..b82e691a 100644
--- a/gpu/demos/app_framework/application.cc
+++ b/gpu/demos/app_framework/application.cc
@@ -74,7 +74,15 @@ void Application::MainLoop() {
 }
 
 void Application::OnPaint() {
-  Draw();
+  float elapsed_sec = 0.0f;
+  const base::Time current_time = base::Time::Now();
+  if (!last_draw_time_.is_null()) {
+    base::TimeDelta time_delta = current_time - last_draw_time_;
+    elapsed_sec = static_cast<float>(time_delta.InSecondsF());
+  }
+  last_draw_time_ = current_time;
+
+  Draw(elapsed_sec);
   gles2::GetGLContext()->SwapBuffers();
 }
 
diff --git a/gpu/demos/app_framework/application.h b/gpu/demos/app_framework/application.h
index f7d1a50..d9d48e9 100644
--- a/gpu/demos/app_framework/application.h
+++ b/gpu/demos/app_framework/application.h
@@ -9,6 +9,7 @@
 
 #include "base/at_exit.h"
 #include "base/message_loop.h"
+#include "base/time.h"
 
 #include "gpu/demos/app_framework/platform.h"
 
@@ -36,7 +37,13 @@ class Application {
 
   bool InitRenderContext();
 
-  virtual void Draw() = 0;
+  // The framework calls this function for the derived classes to do custom
+  // rendering. There is no default implementation. It must be defined by the
+  // derived classes. The elapsed_sec param represents the time elapsed
+  // (in seconds) after Draw was called the last time. It can be used to
+  // make the application frame-rate independent. It is 0.0f for the
+  // first draw call.
+  virtual void Draw(float elapsed_sec) = 0;
 
  private:
   // Creates a native on-screen window.
@@ -46,6 +53,9 @@ class Application {
   int height_;
   NativeWindowHandle window_handle_;
 
+  // Time at which draw was called last.
+  base::Time last_draw_time_;
+
   // The following two variables are just needed to satisfy
   // the assumption that we are running inside a browser.
   base::AtExitManager at_exit_manager_;
diff --git a/gpu/demos/hello_triangle/main.cc b/gpu/demos/hello_triangle/main.cc
index 573b1c9..3f75bc9 100644
--- a/gpu/demos/hello_triangle/main.cc
+++ b/gpu/demos/hello_triangle/main.cc
@@ -19,7 +19,7 @@ class HelloTriangle : public Application {
   bool Init();
 
  protected:
-  virtual void Draw();
+  virtual void Draw(float);
 
  private:
   ESContext context_;
@@ -49,7 +49,7 @@ bool HelloTriangle::Init() {
   return true;
 }
 
-void HelloTriangle::Draw() {
+void HelloTriangle::Draw(float) {
   htDraw(&context_);
 }
 }  // namespace gpu_demos
diff --git a/gpu/demos/simple_vertex_shader/main.cc b/gpu/demos/simple_vertex_shader/main.cc
index d042942..350c5d7 100644
--- a/gpu/demos/simple_vertex_shader/main.cc
+++ b/gpu/demos/simple_vertex_shader/main.cc
@@ -19,7 +19,7 @@ class SimpleVertexShader : public Application {
   bool Init();
 
  protected:
-  virtual void Draw();
+  virtual void Draw(float elapsed_sec);
 
  private:
   ESContext context_;
@@ -45,12 +45,13 @@ bool SimpleVertexShader::Init() {
   context_.width = width();
   context_.height = height();
   if (!svsInit(&context_)) return false;
-  svsUpdate(&context_, 0.0f);
 
   return true;
 }
 
-void SimpleVertexShader::Draw() {
+void SimpleVertexShader::Draw(float elapsed_sec) {
+  svsUpdate(&context_, elapsed_sec);
+
   svsDraw(&context_);
 }
 }  // namespace gpu_demos