VIDEO: Allow setting alpha blending mode.

sim_video.c

@@ -370,6 +370,7 @@ t_bool vid_cursor_visible;                              /* cursor visibility sta
 DEVICE *vid_dev;
 t_bool vid_key_state[SDL_NUM_SCANCODES];
 VID_DISPLAY *next;
+t_bool vid_blending;
 };
 
 SDL_Thread *vid_thread_handle = NULL;                   /* event thread handle */
@@ -625,6 +626,7 @@ vptr->vid_width = width;
 vptr->vid_height = height;
 vptr->vid_mouse_captured = FALSE;
 vptr->vid_cursor_visible = (vptr->vid_flags & SIM_VID_INPUTCAPTURED);
+vptr->vid_blending = FALSE;
 
 if (!vid_active) {
     vid_key_events.head = 0;
@@ -786,6 +788,11 @@ uint32 vid_map_rgb (uint8 r, uint8 g, uint8 b)
 return vid_map_rgb_window (&vid_first, r, g, b);
 }
 
+uint32 vid_map_rgba_window (VID_DISPLAY *vptr, uint8 r, uint8 g, uint8 b, uint8 a)
+{
+return SDL_MapRGBA (vptr->vid_format, r, g, b, a);
+}
+
 static SDL_Rect *vid_dst_last;
 static uint32 *vid_data_last;
 
@@ -1574,11 +1581,15 @@ vid_stretch(vptr, &vid_dst);
 sim_debug (SIM_VID_DBG_VIDEO, vptr->vid_dev, "Video Update Event: \n");
 if (sim_deb)
     fflush (sim_deb);
-if (SDL_RenderClear (vptr->vid_renderer))
+if (vptr->vid_blending)
+    SDL_RenderPresent (vptr->vid_renderer);
+else {
+    if (SDL_RenderClear (vptr->vid_renderer))
         sim_printf ("%s: Video Update Event: SDL_RenderClear error: %s\n", vid_dname(vptr->vid_dev), SDL_GetError());
-if (SDL_RenderCopy (vptr->vid_renderer, vptr->vid_texture, NULL, &vid_dst))
+    if (SDL_RenderCopy (vptr->vid_renderer, vptr->vid_texture, NULL, &vid_dst))
         sim_printf ("%s: Video Update Event: SDL_RenderCopy error: %s\n", vid_dname(vptr->vid_dev), SDL_GetError());
-SDL_RenderPresent (vptr->vid_renderer);
+    SDL_RenderPresent (vptr->vid_renderer);
+    }
 }
 
 void vid_update_cursor (VID_DISPLAY *vptr, SDL_Cursor *cursor, t_bool visible)
@@ -1620,7 +1631,12 @@ if (vid_dst == vid_dst_last) {
     }
 SDL_UnlockMutex (vptr->vid_draw_mutex);
 
-if (SDL_UpdateTexture(vptr->vid_texture, vid_dst, buf, vid_dst->w*sizeof(*buf)))
+if (vptr->vid_blending) {
+    SDL_UpdateTexture(vptr->vid_texture, vid_dst, buf, vid_dst->w*sizeof(*buf));
+    SDL_RenderCopy (vptr->vid_renderer, vptr->vid_texture, vid_dst, vid_dst); 
+    }
+else
+    if (SDL_UpdateTexture(vptr->vid_texture, vid_dst, buf, vid_dst->w*sizeof(*buf)))
         sim_printf ("%s: vid_draw_region() - SDL_UpdateTexture error: %s\n", vid_dname(vptr->vid_dev), SDL_GetError());
 
 free (vid_dst);
@@ -1688,6 +1704,36 @@ vid_active++;
 return 1;
 }
 
+t_stat vid_set_alpha_mode (VID_DISPLAY *vptr, int mode)
+{
+SDL_BlendMode x;
+switch (mode) {
+    case SIM_ALPHA_NONE:
+        vptr->vid_blending = FALSE;
+        x = SDL_BLENDMODE_NONE;
+        break;
+    case SIM_ALPHA_BLEND:
+        vptr->vid_blending = TRUE;
+        x = SDL_BLENDMODE_BLEND;
+        break;
+    case SIM_ALPHA_ADD:
+        vptr->vid_blending = TRUE;
+        x = SDL_BLENDMODE_ADD;
+        break;
+    case SIM_ALPHA_MOD:
+        vptr->vid_blending = TRUE;
+        x = SDL_BLENDMODE_MOD;
+        break;
+    default:
+        return SCPE_ARG;
+    }
+if (SDL_SetTextureBlendMode (vptr->vid_texture, x))
+    return SCPE_IERR;
+if (SDL_SetRenderDrawBlendMode (vptr->vid_renderer, x))
+    return SCPE_IERR;
+return SCPE_OK;
+}
+
 static void vid_destroy (VID_DISPLAY *vptr)
 {
 VID_DISPLAY *parent;

sim_video.h

@@ -157,6 +157,11 @@ extern "C" {
 
 #define SIM_KEY_UNKNOWN        200
 
+#define SIM_ALPHA_NONE         1
+#define SIM_ALPHA_BLEND        2
+#define SIM_ALPHA_ADD          3
+#define SIM_ALPHA_MOD          4
+
 typedef struct VID_DISPLAY VID_DISPLAY;
 
 struct mouse_event {
@@ -214,12 +219,14 @@ t_stat vid_open_window (VID_DISPLAY **vptr, DEVICE *dptr, const char *title, uin
 t_stat vid_close_window (VID_DISPLAY *vptr);
 t_stat vid_close_all (void);
 uint32 vid_map_rgb_window (VID_DISPLAY *vptr, uint8 r, uint8 g, uint8 b);
+uint32 vid_map_rgba_window (VID_DISPLAY *vptr, uint8 r, uint8 g, uint8 b, uint8 a);
 void vid_draw_window (VID_DISPLAY *vptr, int32 x, int32 y, int32 w, int32 h, uint32 *buf);
 void vid_refresh_window (VID_DISPLAY *vptr);
 t_stat vid_set_cursor_window (VID_DISPLAY *vptr, t_bool visible, uint32 width, uint32 height, uint8 *data, uint8 *mask, uint32 hot_x, uint32 hot_y);
 t_bool vid_is_fullscreen_window (VID_DISPLAY *vptr);
 t_stat vid_set_fullscreen_window (VID_DISPLAY *vptr, t_bool flag);
 void vid_set_cursor_position_window (VID_DISPLAY *vptr, int32 x, int32 y);        /* cursor position (set by calling code) */
+t_stat vid_set_alpha_mode (VID_DISPLAY *vptr, int mode);
 
 /* A device simulator can optionally set the vid_display_kb_event_process
  * routine pointer to the address of a routine.