Backends: OpenGL3: Fixed restoration of a potentially deleted OpenGL program. (#6220, #6224)

backends/imgui_impl_opengl3.cpp

@@ -14,11 +14,12 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2023-03-06: OpenGL: Fixed restoration of a potentially deleted OpenGL program, by calling glIsProgram(). (#6220, #6224)
 //  2022-11-09: OpenGL: Reverted use of glBufferSubData(), too many corruptions issues + old issues seemingly can't be reproed with Intel drivers nowadays (revert 2021-12-15 and 2022-05-23 changes).
 //  2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11.
 //  2022-09-27: OpenGL: Added ability to '#define IMGUI_IMPL_OPENGL_DEBUG'.
 //  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.
+//  2022-05-13: OpenGL: Fixed 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.
 //  2021-08-19: OpenGL: Embed and use our own minimal GL loader (imgui_impl_opengl3_loader.h), removing requirement and support for third-party loader.
@@ -576,7 +577,8 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
 #endif
 
     // Restore modified GL state
-    glUseProgram(last_program);
+    // This "glIsProgram()" check is required because if the program is "pending deletion" at the time of binding backup, it will have been deleted by now and will cause an OpenGL error. See #6220.
+    if (glIsProgram(last_program)) glUseProgram(last_program);
     glBindTexture(GL_TEXTURE_2D, last_texture);
 #ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_BIND_SAMPLER
     if (bd->GlVersion >= 330)

backends/imgui_impl_opengl3_loader.h

@@ -309,6 +309,7 @@ typedef void (APIENTRYP PFNGLGETSHADERINFOLOGPROC) (GLuint shader, GLsizei bufSi
 typedef GLint (APIENTRYP PFNGLGETUNIFORMLOCATIONPROC) (GLuint program, const GLchar *name);
 typedef void (APIENTRYP PFNGLGETVERTEXATTRIBIVPROC) (GLuint index, GLenum pname, GLint *params);
 typedef void (APIENTRYP PFNGLGETVERTEXATTRIBPOINTERVPROC) (GLuint index, GLenum pname, void **pointer);
+typedef GLboolean (APIENTRYP PFNGLISPROGRAMPROC) (GLuint program);
 typedef void (APIENTRYP PFNGLLINKPROGRAMPROC) (GLuint program);
 typedef void (APIENTRYP PFNGLSHADERSOURCEPROC) (GLuint shader, GLsizei count, const GLchar *const*string, const GLint *length);
 typedef void (APIENTRYP PFNGLUSEPROGRAMPROC) (GLuint program);
@@ -334,6 +335,7 @@ GLAPI void APIENTRY glGetShaderInfoLog (GLuint shader, GLsizei bufSize, GLsizei
 GLAPI GLint APIENTRY glGetUniformLocation (GLuint program, const GLchar *name);
 GLAPI void APIENTRY glGetVertexAttribiv (GLuint index, GLenum pname, GLint *params);
 GLAPI void APIENTRY glGetVertexAttribPointerv (GLuint index, GLenum pname, void **pointer);
+GLAPI GLboolean APIENTRY glIsProgram (GLuint program);
 GLAPI void APIENTRY glLinkProgram (GLuint program);
 GLAPI void APIENTRY glShaderSource (GLuint shader, GLsizei count, const GLchar *const*string, const GLint *length);
 GLAPI void APIENTRY glUseProgram (GLuint program);
@@ -462,7 +464,7 @@ GL3W_API GL3WglProc imgl3wGetProcAddress(const char *proc);
 
 /* gl3w internal state */
 union GL3WProcs {
-    GL3WglProc ptr[58];
+    GL3WglProc ptr[59];
     struct {
         PFNGLACTIVETEXTUREPROC            ActiveTexture;
         PFNGLATTACHSHADERPROC             AttachShader;
@@ -509,6 +511,7 @@ union GL3WProcs {
         PFNGLGETVERTEXATTRIBPOINTERVPROC  GetVertexAttribPointerv;
         PFNGLGETVERTEXATTRIBIVPROC        GetVertexAttribiv;
         PFNGLISENABLEDPROC                IsEnabled;
+        PFNGLISPROGRAMPROC                IsProgram;
         PFNGLLINKPROGRAMPROC              LinkProgram;
         PFNGLPIXELSTOREIPROC              PixelStorei;
         PFNGLPOLYGONMODEPROC              PolygonMode;
@@ -573,6 +576,7 @@ GL3W_API extern union GL3WProcs imgl3wProcs;
 #define glGetVertexAttribPointerv         imgl3wProcs.gl.GetVertexAttribPointerv
 #define glGetVertexAttribiv               imgl3wProcs.gl.GetVertexAttribiv
 #define glIsEnabled                       imgl3wProcs.gl.IsEnabled
+#define glIsProgram                       imgl3wProcs.gl.IsProgram
 #define glLinkProgram                     imgl3wProcs.gl.LinkProgram
 #define glPixelStorei                     imgl3wProcs.gl.PixelStorei
 #define glPolygonMode                     imgl3wProcs.gl.PolygonMode
@@ -770,6 +774,7 @@ static const char *proc_names[] = {
     "glGetVertexAttribPointerv",
     "glGetVertexAttribiv",
     "glIsEnabled",
+    "glIsProgram",
     "glLinkProgram",
     "glPixelStorei",
     "glPolygonMode",

docs/CHANGELOG.txt

@@ -51,6 +51,8 @@ Other changes:
   before and can accept the same data type. (#6183).
 - Drag and Drop: Clear drag and drop state as soon as delivery is accepted in order to
   avoid inteferences. (#5817, #6183) [@DimaKoltun]
+- Backends: OpenGL3: Fixed restoration of a potentially deleted OpenGL program. If an active
+  program was pending deletion, attempting to restore it would error. (#6220, #6224) [@Cyphall]
 - Backends: Win32: Use WM_NCMOUSEMOVE / WM_NCMOUSELEAVE to track mouse positions over
   non-client area (e.g. OS decorations) when app is not focused. (#6045, #6162)
 - Backends: SDL2, SDL3:  Accept SDL_GetPerformanceCounter() not returning a monotonically