Examples: OpenGL3: cleaned up to match features of OpenGL2 example

examples/opengl3_example/main.cpp

@@ -20,14 +20,9 @@ static ImVec2 mousePosScale(1.0f, 1.0f);
 
 // Shader variables
 static int shader_handle, vert_handle, frag_handle;
-
 static int texture_location, ortho_location;
 static int position_location, uv_location, colour_location;
-//streaming vbo
+static size_t vbo_max_size = 20000;
-//we are going to use the same vertex buffer for all rendering of imgui
-//so we need to use a large enough buffer as default.
-//the buffer will be resized if needed in the rendering code, but it is not a "free" operation.
-static size_t vbo_max_size = 1000000;
 static unsigned int vbo_handle, vao_handle;
 
 // This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
@@ -65,19 +60,19 @@ static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_c
     glUniform1i(texture_location, 0);
     glUniformMatrix4fv(ortho_location, 1, GL_FALSE, &ortho_projection[0][0]);
 
-    // we will update the buffer in full, so we need to compute the total size of the buffer.
+	// Grow our buffer according to what we need
     size_t total_vtx_count = 0;
     for (int n = 0; n < cmd_lists_count; n++)
         total_vtx_count += cmd_lists[n]->vtx_buffer.size();
-
     glBindBuffer(GL_ARRAY_BUFFER, vbo_handle);
     size_t neededBufferSize = total_vtx_count * sizeof(ImDrawVert);
     if (neededBufferSize > vbo_max_size)
     {
-        vbo_max_size = neededBufferSize;
+        vbo_max_size = neededBufferSize + 5000;  // Grow buffer
-        glBufferData(GL_ARRAY_BUFFER, total_vtx_count * sizeof(ImDrawVert), NULL, GL_STREAM_DRAW);
+        glBufferData(GL_ARRAY_BUFFER, neededBufferSize, NULL, GL_STREAM_DRAW);
     }
 
+	// Copy and convert all vertices into a single contiguous buffer
     unsigned char* buffer_data = (unsigned char*)glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
     if (!buffer_data)
         return;
@@ -89,7 +84,6 @@ static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_c
     }
     glUnmapBuffer(GL_ARRAY_BUFFER);
     glBindBuffer(GL_ARRAY_BUFFER, 0);
-
     glBindVertexArray(vao_handle);
 
     int cmd_offset = 0;
@@ -107,11 +101,11 @@ static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_c
         cmd_offset = vtx_offset;
     }
 
+	// Restore modified state
     glBindVertexArray(0);
     glUseProgram(0);
     glDisable(GL_SCISSOR_TEST);
     glBindTexture(GL_TEXTURE_2D, 0);
-
 }
 
 static const char* ImImpl_GetClipboardTextFn()
@@ -159,7 +153,6 @@ static void glfw_char_callback(GLFWwindow* window, unsigned int c)
         ImGui::GetIO().AddInputCharacter((unsigned short)c);
 }
 
-
 // OpenGL code based on http://open.gl tutorials
 void InitGL()
 {
@@ -183,11 +176,9 @@ void InitGL()
 
     GLenum err = glewInit();
     if (GLEW_OK != err)
-    {
         fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
-    }
 
-    const GLchar *vertex_shader =   \
+    const GLchar *vertex_shader =
 		"#version 330\n"
 		"uniform mat4 ortho;\n"
 		"in vec2 Position;\n"
@@ -202,7 +193,7 @@ void InitGL()
 		"	gl_Position = ortho*vec4(Position.xy,0,1);\n"
 		"}\n";
 
-    const GLchar* fragment_shader = \
+    const GLchar* fragment_shader =
 		"#version 330\n"
 		"uniform sampler2D Texture;\n"
 		"in vec2 Frag_UV;\n"
@@ -246,17 +237,19 @@ void InitGL()
     glVertexAttribPointer(colour_location, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (GLvoid*) offsetof(ImDrawVert, col));
     glBindVertexArray(0);
     glBindBuffer(GL_ARRAY_BUFFER, 0);
-
-
 }
 
 void InitImGui()
 {
 	int w, h;
+	int display_w, display_h;
 	glfwGetWindowSize(window, &w, &h);
+	glfwGetFramebufferSize(window, &display_w, &display_h);
+	mousePosScale.x = (float)display_w / w;                       // Some screens e.g. Retina display have framebuffer size != from window size, and mouse inputs are given in window/screen coordinates.
+	mousePosScale.y = (float)display_h / h;
 
     ImGuiIO& io = ImGui::GetIO();
-    io.DisplaySize = ImVec2((float)w, (float)h);        // Display size, in pixels. For clamping windows positions.
+    io.DisplaySize = ImVec2((float)display_w, (float)display_h);  // Display size, in pixels. For clamping windows positions.
     io.DeltaTime = 1.0f / 60.0f;                                  // Time elapsed since last frame, in seconds (in this sample app we'll override this every frame because our timestep is variable)
     io.PixelCenterOffset = 0.5f;                                  // Align OpenGL texels
     io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB;                       // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
@@ -309,9 +302,9 @@ void UpdateImGui()
     // (we already got mouse wheel, keyboard keys & characters from glfw callbacks polled in glfwPollEvents())
     double mouse_x, mouse_y;
     glfwGetCursorPos(window, &mouse_x, &mouse_y);
-    io.MousePos = ImVec2((float)mouse_x, (float)mouse_y);                           // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
+	io.MousePos = ImVec2((float)mouse_x * mousePosScale.x, (float)mouse_y * mousePosScale.y);      // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
-    io.MouseDown[0] = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT) != 0;
+	io.MouseDown[0] = mousePressed[0] || glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT) != 0;  // If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
-    io.MouseDown[1] = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_RIGHT) != 0;
+	io.MouseDown[1] = mousePressed[1] || glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_RIGHT) != 0;
 
     // Start the frame
     ImGui::NewFrame();
@@ -330,17 +323,19 @@ int main(int argc, char** argv)
         glfwPollEvents();
         UpdateImGui();
 
-        // Create a simple window
-        // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
 		static bool show_test_window = true;
 		static bool show_another_window = false;
+
+		// 1. Show a simple window
+		// Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
+		{
 			static float f;
 			ImGui::Text("Hello, world!");
 			ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
 			show_test_window ^= ImGui::Button("Test Window");
 			show_another_window ^= ImGui::Button("Another Window");
 
-        // Calculate and show framerate
+			// Calculate and show frame rate
 			static float ms_per_frame[120] = { 0 };
 			static int ms_per_frame_idx = 0;
 			static float ms_per_frame_accum = 0.0f;
@@ -350,16 +345,9 @@ int main(int argc, char** argv)
 			ms_per_frame_idx = (ms_per_frame_idx + 1) % 120;
 			const float ms_per_frame_avg = ms_per_frame_accum / 120;
 			ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", ms_per_frame_avg, 1000.0f / ms_per_frame_avg);
-
-        // Show the ImGui test window
-        // Most of user example code is in ImGui::ShowTestWindow()
-        if (show_test_window)
-        {
-            ImGui::SetNewWindowDefaultPos(ImVec2(650, 20));        // Normally user code doesn't need/want to call it because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
-            ImGui::ShowTestWindow(&show_test_window);
 		}
 
-        // Show another simple window
+		// 2. Show another simple window, this time using an explicit Begin/End pair
 		if (show_another_window)
 		{
 			ImGui::Begin("Another Window", &show_another_window, ImVec2(200,100));
@@ -367,6 +355,13 @@ int main(int argc, char** argv)
 			ImGui::End();
 		}
 
+		// 3. Show the ImGui test window. Most of the sample code is in ImGui::ShowTestWindow()
+		if (show_test_window)
+		{
+			ImGui::SetNewWindowDefaultPos(ImVec2(650, 20));        // Normally user code doesn't need/want to call this, because positions are saved in .ini file. Here we just want to make the demo initial state a bit more friendly!
+			ImGui::ShowTestWindow(&show_test_window);
+		}
+		
 		// Rendering
         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
         glClearColor(0.8f, 0.6f, 0.6f, 1.0f);
@@ -374,6 +369,8 @@ int main(int argc, char** argv)
         ImGui::Render();
         glfwSwapBuffers(window);
     }
+
+	// Cleanup
     if (vao_handle) glDeleteVertexArrays(1, &vao_handle);
     if (vbo_handle) glDeleteBuffers(1, &vbo_handle);
     glDetachShader(shader_handle, vert_handle);

examples/opengl_example/main.cpp

@@ -305,7 +305,9 @@ int main(int argc, char** argv)
         glfwSwapBuffers(window);
     }
 
+	// Cleanup
     ImGui::Shutdown();
     glfwTerminate();
+
 	return 0;
 }