Examples: OpenGL3: simplified code using glBufferData for vertices as well (#277, #278)

examples/opengl3_example/imgui_impl_glfw_gl3.cpp

@@ -23,7 +23,6 @@ static GLuint       g_FontTexture = 0;
 static int          g_ShaderHandle = 0, g_VertHandle = 0, g_FragHandle = 0;
 static int          g_AttribLocationTex = 0, g_AttribLocationProjMtx = 0;
 static int          g_AttribLocationPosition = 0, g_AttribLocationUV = 0, g_AttribLocationColor = 0;
-static int          g_VboSize = 0;
 static unsigned int g_VboHandle = 0, g_VaoHandle = 0, g_ElementsHandle = 0;
 
 // This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
@@ -64,22 +63,10 @@ static void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
         const ImDrawIdx* idx_buffer_offset = 0;
 
         glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
-        int needed_vtx_size = cmd_list->VtxBuffer.size() * sizeof(ImDrawVert);
-        if (g_VboSize < needed_vtx_size)
-        {
-            // Grow our buffer if needed
-            g_VboSize = needed_vtx_size + 2000 * sizeof(ImDrawVert);
-            glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)g_VboSize, NULL, GL_STREAM_DRAW);
-        }
-
-        unsigned char* vtx_data = (unsigned char*)glMapBufferRange(GL_ARRAY_BUFFER, 0, needed_vtx_size, GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT);
-        if (!vtx_data)
-            continue;
-        memcpy(vtx_data, &cmd_list->VtxBuffer[0], cmd_list->VtxBuffer.size() * sizeof(ImDrawVert));
-        glUnmapBuffer(GL_ARRAY_BUFFER);
+        glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.size() * sizeof(ImDrawVert), (GLvoid*)&cmd_list->VtxBuffer.front(), GL_STREAM_DRAW);
 
         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_ElementsHandle);
-        glBufferData(GL_ELEMENT_ARRAY_BUFFER, cmd_list->IdxBuffer.size() * sizeof(ImDrawIdx), (GLvoid*)&cmd_list->IdxBuffer.front(), GL_STREAM_DRAW);
+        glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.size() * sizeof(ImDrawIdx), (GLvoid*)&cmd_list->IdxBuffer.front(), GL_STREAM_DRAW);
 
         for (const ImDrawCmd* pcmd = cmd_list->CmdBuffer.begin(); pcmd != cmd_list->CmdBuffer.end(); pcmd++)
         {