Commit 354cabd4a7ae73121a527980d7cef9dae41e9d3a
2021-04-03T18:15:50
egl: favor truecolor configurations. If app requested <= 16 color depth and there is a 24-bit config available, favor that. This fixes things that quietly expect to get truecolor output but don't request it (...like SDL's render api...) and things that are probably requesting 16-bit color as a fallback but expecting reasonable systems to give them full depth. Specifically, this fixes Life is Strange on Wayland, which uses the latter approach, and anything using SDL_Render on Wayland, which uses the former. Fixes #4056. Fixes #4132.
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diff --git a/src/video/SDL_egl.c b/src/video/SDL_egl.c
index 3716da7..0eb4c85 100644
--- a/src/video/SDL_egl.c
+++ b/src/video/SDL_egl.c
@@ -700,7 +700,8 @@ SDL_EGL_ChooseConfig(_THIS)
/* 128 seems even nicer here */
EGLConfig configs[128];
SDL_bool has_matching_format = SDL_FALSE;
- int i, j, best_bitdiff = -1, bitdiff;
+ int i, j, best_bitdiff = -1, best_truecolor_bitdiff = -1;
+ int truecolor_config_idx = -1;
if (!_this->egl_data) {
/* The EGL library wasn't loaded, SDL_GetError() should have info */
@@ -804,17 +805,30 @@ SDL_EGL_ChooseConfig(_THIS)
/* From those, we select the one that matches our requirements more closely via a makeshift algorithm */
for (i = 0; i < found_configs; i++ ) {
- if (has_matching_format && _this->egl_data->egl_required_visual_id)
- {
+ SDL_bool is_truecolor = SDL_FALSE;
+ int bitdiff = 0;
+
+ if (has_matching_format && _this->egl_data->egl_required_visual_id) {
EGLint format;
_this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display,
configs[i],
EGL_NATIVE_VISUAL_ID, &format);
- if (_this->egl_data->egl_required_visual_id != format)
+ if (_this->egl_data->egl_required_visual_id != format) {
continue;
+ }
+ }
+
+ _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, configs[i], EGL_RED_SIZE, &value);
+ if (value == 8) {
+ _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, configs[i], EGL_GREEN_SIZE, &value);
+ if (value == 8) {
+ _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, configs[i], EGL_BLUE_SIZE, &value);
+ if (value == 8) {
+ is_truecolor = SDL_TRUE;
+ }
+ }
}
- bitdiff = 0;
for (j = 0; j < SDL_arraysize(attribs) - 1; j += 2) {
if (attribs[j] == EGL_NONE) {
break;
@@ -832,16 +846,37 @@ SDL_EGL_ChooseConfig(_THIS)
}
}
- if (bitdiff < best_bitdiff || best_bitdiff == -1) {
+ if ((bitdiff < best_bitdiff) || (best_bitdiff == -1)) {
_this->egl_data->egl_config = configs[i];
-
best_bitdiff = bitdiff;
}
- if (bitdiff == 0) {
- break; /* we found an exact match! */
+ if (is_truecolor && ((bitdiff < best_truecolor_bitdiff) || (best_truecolor_bitdiff == -1))) {
+ truecolor_config_idx = i;
+ best_truecolor_bitdiff = bitdiff;
+ }
+ }
+
+ #define FAVOR_TRUECOLOR 1
+ #if FAVOR_TRUECOLOR
+ /* Some apps request a low color depth, either because they _assume_
+ they'll get a larger one but don't want to fail if only smaller ones
+ are available, or they just never called SDL_GL_SetAttribute at all and
+ got a tiny default. For these cases, a game that would otherwise run
+ at 24-bit color might get dithered down to something smaller, which is
+ worth avoiding. If the app requested <= 16 bit color and an exact 24-bit
+ match is available, favor that. Otherwise, we look for the closest
+ match. Note that while the API promises what you request _or better_,
+ it's feasible this can be disastrous for performance for custom software
+ on small hardware that all expected to actually get 16-bit color. In this
+ case, turn off FAVOR_TRUECOLOR (and maybe send a patch to make this more
+ flexible). */
+ if ( ((_this->gl_config.red_size + _this->gl_config.blue_size + _this->gl_config.green_size) <= 16) ) {
+ if (truecolor_config_idx != -1) {
+ _this->egl_data->egl_config = configs[truecolor_config_idx];
}
}
+ #endif
#ifdef DUMP_EGL_CONFIG
dumpconfig(_this, _this->egl_data->egl_config);