Backends: OpenGL: Partially revert 1.86 change of using glBufferSubData(): now only done on Intel GPUs. (#4468, #3381, #2981, #4825, #4832, #5127)
Essentially reverts 389982eb for non-Intel GPUs + update imgui_impl_opengl3_loader.h
Amended once (force-pushed).
diff --git a/backends/imgui_impl_opengl3.cpp b/backends/imgui_impl_opengl3.cpp
index 0347e1d..7896a59 100644
--- a/backends/imgui_impl_opengl3.cpp
+++ b/backends/imgui_impl_opengl3.cpp
@@ -14,6 +14,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2022-05-23: OpenGL: Reworking 2021-12-15 "Using buffer orphaning" so it only happens on Intel GPU, seems to cause problems otherwise. (#4468, #4825, #4832, #5127).
// 2022-05-13: OpenGL: Fix state corruption on OpenGL ES 2.0 due to not preserving GL_ELEMENT_ARRAY_BUFFER_BINDING and vertex attribute states.
// 2021-12-15: OpenGL: Using buffer orphaning + glBufferSubData(), seems to fix leaks with multi-viewports with some Intel HD drivers.
// 2021-08-23: OpenGL: Fixed ES 3.0 shader ("#version 300 es") use normal precision floats to avoid wobbly rendering at HD resolutions.
@@ -193,6 +194,7 @@
GLsizeiptr VertexBufferSize;
GLsizeiptr IndexBufferSize;
bool HasClipOrigin;
+ bool UseBufferSubData;
ImGui_ImplOpenGL3_Data() { memset((void*)this, 0, sizeof(*this)); }
};
@@ -261,6 +263,14 @@
sscanf(gl_version, "%d.%d", &major, &minor);
}
bd->GlVersion = (GLuint)(major * 100 + minor * 10);
+
+ // Query vendor to enable glBufferSubData kludge
+#ifdef _WIN32
+ if (const char* vendor = (const char*)glGetString(GL_VENDOR))
+ if (strncmp(vendor, "Intel", 5) == 0)
+ bd->UseBufferSubData = true;
+#endif
+ //printf("GL_MAJOR_VERSION = %d\nGL_MINOR_VERSION = %d\nGL_VENDOR = '%s'\nGL_RENDERER = '%s'\n", major, minor, (const char*)glGetString(GL_VENDOR), (const char*)glGetString(GL_RENDERER)); // [DEBUG]
#else
bd->GlVersion = 200; // GLES 2
#endif
@@ -474,20 +484,31 @@
const ImDrawList* cmd_list = draw_data->CmdLists[n];
// Upload vertex/index buffers
- GLsizeiptr vtx_buffer_size = (GLsizeiptr)cmd_list->VtxBuffer.Size * (int)sizeof(ImDrawVert);
- GLsizeiptr idx_buffer_size = (GLsizeiptr)cmd_list->IdxBuffer.Size * (int)sizeof(ImDrawIdx);
- if (bd->VertexBufferSize < vtx_buffer_size)
+ // - On Intel windows drivers we got reports that regular glBufferData() led to accumulating leaks when using multi-viewports, so we started using orphaning + glBufferSubData(). (See https://github.com/ocornut/imgui/issues/4468)
+ // - On NVIDIA drivers we got reports that using orphaning + glBufferSubData() led to glitches when using multi-viewports.
+ // - OpenGL drivers are in a very sorry state in 2022, for now we are switching code path based on vendors.
+ const GLsizeiptr vtx_buffer_size = (GLsizeiptr)cmd_list->VtxBuffer.Size * (int)sizeof(ImDrawVert);
+ const GLsizeiptr idx_buffer_size = (GLsizeiptr)cmd_list->IdxBuffer.Size * (int)sizeof(ImDrawIdx);
+ if (bd->UseBufferSubData)
{
- bd->VertexBufferSize = vtx_buffer_size;
- glBufferData(GL_ARRAY_BUFFER, bd->VertexBufferSize, NULL, GL_STREAM_DRAW);
+ if (bd->VertexBufferSize < vtx_buffer_size)
+ {
+ bd->VertexBufferSize = vtx_buffer_size;
+ glBufferData(GL_ARRAY_BUFFER, bd->VertexBufferSize, NULL, GL_STREAM_DRAW);
+ }
+ if (bd->IndexBufferSize < idx_buffer_size)
+ {
+ bd->IndexBufferSize = idx_buffer_size;
+ glBufferData(GL_ELEMENT_ARRAY_BUFFER, bd->IndexBufferSize, NULL, GL_STREAM_DRAW);
+ }
+ glBufferSubData(GL_ARRAY_BUFFER, 0, vtx_buffer_size, (const GLvoid*)cmd_list->VtxBuffer.Data);
+ glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, idx_buffer_size, (const GLvoid*)cmd_list->IdxBuffer.Data);
}
- if (bd->IndexBufferSize < idx_buffer_size)
+ else
{
- bd->IndexBufferSize = idx_buffer_size;
- glBufferData(GL_ELEMENT_ARRAY_BUFFER, bd->IndexBufferSize, NULL, GL_STREAM_DRAW);
+ glBufferData(GL_ARRAY_BUFFER, vtx_buffer_size, (const GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW);
+ glBufferData(GL_ELEMENT_ARRAY_BUFFER, idx_buffer_size, (const GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW);
}
- glBufferSubData(GL_ARRAY_BUFFER, 0, vtx_buffer_size, (const GLvoid*)cmd_list->VtxBuffer.Data);
- glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, idx_buffer_size, (const GLvoid*)cmd_list->IdxBuffer.Data);
for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
{
diff --git a/backends/imgui_impl_opengl3_loader.h b/backends/imgui_impl_opengl3_loader.h
index 67ac389..d576235 100644
--- a/backends/imgui_impl_opengl3_loader.h
+++ b/backends/imgui_impl_opengl3_loader.h
@@ -164,6 +164,8 @@
#define GL_FLOAT 0x1406
#define GL_RGBA 0x1908
#define GL_FILL 0x1B02
+#define GL_VENDOR 0x1F00
+#define GL_RENDERER 0x1F01
#define GL_VERSION 0x1F02
#define GL_EXTENSIONS 0x1F03
#define GL_LINEAR 0x2601
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 6dc978e..fe93cbd 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -121,6 +121,13 @@
- Backends: OSX: Monitor NSKeyUp events to catch missing keyUp for key when user press Cmd + key (#5128) [@thedmd]
- Backends: OSX, Metal: Store backend data in a per-context struct, allowing to use these backends with
multiple contexts. (#5203, #5221, #4141) [@noisewuwei]
+- Backends: OpenGL3: Partially revert 1.86 change of using glBufferSubData(): now only done on Windows and
+ Intel GPU, based on querying glGetString(GL_VENDOR). Essentially we got report of accumulating leaks on Intel
+ with multi-viewports when using simple glBufferData() without orphaning, and report of corruptions on other
+ GPUs with multi-viewports when using orphaning and glBufferSubData(), so currently switching technique based
+ on GPU vendor, which unfortunately reinforce the cargo-cult nature of dealing with OpenGL drivers.
+ Navigating the space of mysterious OpenGL drivers is particularly difficult as they are known to rely on
+ application specific whitelisting. (#4468, #3381, #2981, #4825, #4832, #5127).
- Backends: OpenGL3: Fix state corruption on OpenGL ES 2.0 due to not preserving GL_ELEMENT_ARRAY_BUFFER_BINDING
and vertex attribute states. [@rokups]
- Examples: Emscripten+WebGPU: Fix building for latest WebGPU specs. (#3632)
