From 6f0cb752aafc009073135c89730de6fc39a32c59 Mon Sep 17 00:00:00 2001
From: fgsfds <derp.primus@gmail.com>
Date: Thu, 19 Oct 2023 13:36:40 +0200
Subject: [PATCH] port: gl: allow user to override context version

---
 port/fast3d/gfx_sdl2.cpp | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/port/fast3d/gfx_sdl2.cpp b/port/fast3d/gfx_sdl2.cpp
index 7127d0e38..d6eefb1c6 100644
--- a/port/fast3d/gfx_sdl2.cpp
+++ b/port/fast3d/gfx_sdl2.cpp
@@ -94,15 +94,30 @@ static void gfx_sdl_init(const char* game_name, const char* gfx_api_name, bool s
 
     // ideally we need 3.0 compat
     // if that doesn't work, try 3.2 core in case we're on mac, 2.1 compat as a last resort
-    static const u32 glver[][3] = {
+    static u32 glver[][3] = {
+        { 0, 0, 0                                    }, // for command line override
         { 3, 0, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY },
         { 3, 2, SDL_GL_CONTEXT_PROFILE_CORE },
         { 2, 1, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY },
     };
 
+    u32 glcore = false;
+    u32 verstart = 1;
+    const u32 verend = sizeof(glver) / sizeof(*glver);
+    const char *verstr = sysArgGetString("--gl-version");
+    if (verstr && *verstr) {
+        // user override
+        glver[0][2] = strstr(verstr, "core") ? SDL_GL_CONTEXT_PROFILE_CORE :
+            SDL_GL_CONTEXT_PROFILE_COMPATIBILITY;
+        sscanf(verstr, "%d.%d", &glver[0][0], &glver[0][1]);
+        if (glver[0][0] >= 1 && glver[0][0] <= 4 && glver[0][1] < 9) {
+            verstart = 0;
+        }
+    }
+
     ctx = NULL;
     u32 vmin = 0, vmaj = 0;
-    for (u32 i = 0; i < sizeof(glver) / sizeof(*glver); ++i) {
+    for (u32 i = verstart; i < verend; ++i) {
         vmaj = glver[i][0];
         vmin = glver[i][1];
         SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, vmaj);
@@ -112,6 +127,7 @@ static void gfx_sdl_init(const char* game_name, const char* gfx_api_name, bool s
         if (!ctx) {
             sysLogPrintf(LOG_WARNING, "GL: could not create GL%d.%d context: %s", vmaj, vmin, SDL_GetError());
         } else {
+            glcore = (glver[i][2] == SDL_GL_CONTEXT_PROFILE_CORE);
             break;
         }
     }
@@ -119,7 +135,7 @@ static void gfx_sdl_init(const char* game_name, const char* gfx_api_name, bool s
     if (!ctx) {
         sysFatalError("Could not create an OpenGL context of any supported version.\nSDL error: %s", SDL_GetError());
     } else {
-        sysLogPrintf(LOG_NOTE, "GL: created GL%d.%d context", vmaj, vmin);
+        sysLogPrintf(LOG_NOTE, "GL: created GL%d.%d%s context", vmaj, vmin, glcore ? "core" : "");
     }
 
     SDL_GL_MakeCurrent(wnd, ctx);