frame_buffer: updated aspect ratio handling

rxdu · Nov 5, 2024 · f3f75f0 · f3f75f0
1 parent 62dc3fe
commit f3f75f0
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Showing 4 changed files with 37 additions and 19 deletions.
diff --git a/src/app/panels/scene_panel.cpp b/src/app/panels/scene_panel.cpp
@@ -26,6 +26,7 @@ ScenePanel::ScenePanel(const std::string& panel_name) : GlWidget(panel_name) {
 
 void ScenePanel::Draw() {
   ImVec2 content_size = ImGui::GetContentRegionAvail();
+
   // Orthographic projection for a top-down view
   float aspect_ratio =
       static_cast<float>(content_size.x) / static_cast<float>(content_size.y);

diff --git a/src/imview/include/imview/component/opengl/frame_buffer.hpp b/src/imview/include/imview/component/opengl/frame_buffer.hpp
@@ -24,7 +24,7 @@ class FrameBuffer {
   FrameBuffer& operator=(FrameBuffer&&) = delete;
 
   // public methods
-  void Bind() const;
+  void Bind(bool lock_aspect_ratio = true) const;
   void Unbind() const;
   void Clear(float r = 0.0, float g = 0.0, float b = 0.0, float a = 1.0) const;
   uint32_t GetTextureId() const { return texture_buffer_; }
@@ -37,6 +37,8 @@ class FrameBuffer {
   void CreateBuffers();
   void DestroyBuffers();
 
+  float aspect_ratio_ = 1.0;
+  bool lock_aspect_ratio_ = true;
   uint32_t width_;
   uint32_t height_;
   uint32_t frame_buffer_;

diff --git a/src/imview/src/component/opengl/frame_buffer.cpp b/src/imview/src/component/opengl/frame_buffer.cpp
@@ -19,6 +19,7 @@ FrameBuffer::FrameBuffer(uint32_t width, uint32_t height)
       frame_buffer_(0),
       texture_buffer_(0),
       render_buffer_(0) {
+  aspect_ratio_ = static_cast<float>(width) / static_cast<float>(height);
   CreateBuffers();
 }
 
@@ -63,9 +64,21 @@ void FrameBuffer::DestroyBuffers() {
   render_buffer_ = 0;
 }
 
-void FrameBuffer::Bind() const {
+void FrameBuffer::Bind(bool lock_aspect_ratio) const {
   glBindFramebuffer(GL_FRAMEBUFFER, frame_buffer_);
-  glViewport(0, 0, width_, height_);
+
+  if (lock_aspect_ratio) {
+    float expected_width = height_ * aspect_ratio_;
+    if (expected_width > width_) {
+      float actual_height = width_ / aspect_ratio_;
+      glViewport(0, (height_ - actual_height) / 2, width_, actual_height);
+    } else {
+      float actual_width = expected_width;
+      glViewport((width_ - actual_width) / 2, 0, actual_width, height_);
+    }
+  } else {
+    glViewport(0, 0, width_, height_);
+  }
   glEnable(GL_DEPTH_TEST);
 }
 

diff --git a/src/imview/src/widget/gl_widget.cpp b/src/imview/src/widget/gl_widget.cpp
@@ -13,8 +13,6 @@ GlWidget::GlWidget(const std::string& widget_name) : Panel(widget_name) {
   this->SetAutoLayout(false);
   this->SetWindowNoMenuButton();
   this->SetNoBackground(true);
-
-  frame_buffer_ = std::make_unique<FrameBuffer>(100, 50);
 }
 
 void GlWidget::AddOpenGLObject(const std::string& name,
@@ -42,21 +40,25 @@ void GlWidget::Draw() {
     float width = content_size.x;
     float height = content_size.y;
 
-    // render to frame buffer
-    frame_buffer_->Resize(width, height);
-    frame_buffer_->Bind();
-    for (auto& obj : drawable_objects_) {
-      obj.second->OnDraw(projection_, view_);
+    if (frame_buffer_ != nullptr) {
+      // render to frame buffer
+      frame_buffer_->Resize(width, height);
+      frame_buffer_->Bind();
+      for (auto& obj : drawable_objects_) {
+        obj.second->OnDraw(projection_, view_);
+      }
+      frame_buffer_->Unbind();
+
+      // render frame buffer to ImGui
+      ImVec2 uv0 = ImVec2(0, 1);
+      ImVec2 uv1 = ImVec2(1, 0);
+      ImVec4 tint_col = ImVec4(1, 1, 1, 1);
+      ImVec4 border_col = ImVec4(0, 0, 0, 0);
+      ImGui::Image((void*)(intptr_t)frame_buffer_->GetTextureId(),
+                   ImVec2(width, height), uv0, uv1, tint_col, border_col);
+    } else {
+      frame_buffer_ = std::make_unique<FrameBuffer>(width, height);
     }
-    frame_buffer_->Unbind();
-
-    // render frame buffer to ImGui
-    ImVec2 uv0 = ImVec2(0, 1);
-    ImVec2 uv1 = ImVec2(1, 0);
-    ImVec4 tint_col = ImVec4(1, 1, 1, 1);
-    ImVec4 border_col = ImVec4(0, 0, 0, 0);
-    ImGui::Image((void*)(intptr_t)frame_buffer_->GetTextureId(),
-                 ImVec2(width, height), uv0, uv1, tint_col, border_col);
   }
   End();
 }