Add an option to downscale hi-res views

Some older devices that use gpu_unai don't have a high enough
resolution to display all of the pixels in high-res mode. There's a
setting in unai to skip rendering of these pixels, but it's not
connected to the libretro frontend, and does not appear to be used in
the gpulib implementation at all.

This commit adds a gpu_unai setting, Enable Hi-Res Downscaling, that
will enable pixel skipping and blit only the pixels actually rendered
into a buffer no larger than 384x240. This buffer is then treated as
the actual framebuffer by gpulib and the libretro frontend.

5 files changed, 29 insertions, 3 deletions

diff --git a/frontend/libretro.c b/frontend/libretro.c
index 50392a9..8dc6bc3 100644
--- a/frontend/libretro.c
+++ b/frontend/libretro.c
@@ -1999,6 +1999,17 @@ static void update_variables(bool in_flight)
          pl_rearmed_cbs.gpu_unai.blending = 1;
    }
 
+   var.key = "pcsx_rearmed_gpu_unai_scale_hires";
+   var.value = NULL;
+
+   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+   {
+      if (strcmp(var.value, "disabled") == 0)
+         pl_rearmed_cbs.gpu_unai.scale_hires = 0;
+      else if (strcmp(var.value, "enabled") == 0)
+         pl_rearmed_cbs.gpu_unai.scale_hires = 1;
+   }
+
    var.key = "pcsx_rearmed_show_gpu_unai_settings";
    var.value = NULL;
 
@@ -2014,17 +2025,18 @@ static void update_variables(bool in_flight)
       {
          unsigned i;
          struct retro_core_option_display option_display;
-         char gpu_unai_option[5][40] = {
+         char gpu_unai_option[6][40] = {
             "pcsx_rearmed_gpu_unai_blending",
             "pcsx_rearmed_gpu_unai_lighting",
             "pcsx_rearmed_gpu_unai_fast_lighting",
             "pcsx_rearmed_gpu_unai_ilace_force",
-            "pcsx_rearmed_gpu_unai_pixel_skip"
+            "pcsx_rearmed_gpu_unai_pixel_skip",
+            "pcsx_rearmed_gpu_unai_scale_hires"
          };
 
          option_display.visible = show_advanced_gpu_unai_settings;
 
-         for (i = 0; i < 5; i++)
+         for (i = 0; i < 6; i++)
          {
             option_display.key = gpu_unai_option[i];
             environ_cb(RETRO_ENVIRONMENT_SET_CORE_OPTIONS_DISPLAY, &option_display);
diff --git a/frontend/libretro_core_options.h b/frontend/libretro_core_options.h
index 95544f0..283abc6 100644
--- a/frontend/libretro_core_options.h
+++ b/frontend/libretro_core_options.h
@@ -961,6 +961,17 @@ struct retro_core_option_definition option_defs_us[] = {
       },
       "disabled",
    },
+   {
+      "pcsx_rearmed_gpu_unai_scale_hires",
+      "(GPU) Enable Hi-Res Downscaling",
+      "When enabled, will scale hi-res modes to 320x240, skipping unrendered pixels.",
+      {
+         { "disabled", NULL },
+         { "enabled",  NULL },
+         { NULL, NULL},
+      },
+      "disabled",
+   },
 #endif /* GPU UNAI Advanced Settings */
 
    {
diff --git a/frontend/main.c b/frontend/main.c
index b1ee4c7..51cb7bf 100644
--- a/frontend/main.c
+++ b/frontend/main.c
@@ -140,6 +140,7 @@ void emu_set_default_config(void)
 	pl_rearmed_cbs.gpu_unai.abe_hack =
 	pl_rearmed_cbs.gpu_unai.no_light =
 	pl_rearmed_cbs.gpu_unai.no_blend = 0;
+	pl_rearmed_cbs.gpu_unai.scale_hires = 0;
 	memset(&pl_rearmed_cbs.gpu_peopsgl, 0, sizeof(pl_rearmed_cbs.gpu_peopsgl));
 	pl_rearmed_cbs.gpu_peopsgl.iVRamSize = 64;
 	pl_rearmed_cbs.gpu_peopsgl.iTexGarbageCollection = 1;
diff --git a/frontend/menu.c b/frontend/menu.c
index f4a45ba..e5c2738 100644
--- a/frontend/menu.c
+++ b/frontend/menu.c
@@ -432,6 +432,7 @@ static const struct {
 	CE_INTVAL_P(gpu_unai.abe_hack),
 	CE_INTVAL_P(gpu_unai.no_light),
 	CE_INTVAL_P(gpu_unai.no_blend),
+	CE_INTVAL_P(gpu_unai.scale_hires),
 	CE_INTVAL_P(gpu_neon.allow_interlace),
 	CE_INTVAL_P(gpu_neon.enhancement_enable),
 	CE_INTVAL_P(gpu_neon.enhancement_no_main),
diff --git a/frontend/plugin_lib.h b/frontend/plugin_lib.h
index 09cc4c5..ee03169 100644
--- a/frontend/plugin_lib.h
+++ b/frontend/plugin_lib.h
@@ -91,6 +91,7 @@ struct rearmed_cbs {
 		int   abe_hack;
 		int   no_light, no_blend;
 		int   lineskip;
+		int   scale_hires;
 	} gpu_unai;
 	struct {
 		int   dwActFixes;