sdl2/opengl: add opengl context and scanout support

This allows virtio-gpu to render in 3d mode.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

2 files changed, 142 insertions, 0 deletions

diff --git a/ui/sdl2-gl.c b/ui/sdl2-gl.c
index b604c0671e..2bb3d06bab 100644
--- a/ui/sdl2-gl.c
+++ b/ui/sdl2-gl.c
@@ -31,11 +31,37 @@
 #include "ui/sdl2.h"
 #include "sysemu/sysemu.h"
 
+#include <epoxy/gl.h>
+
+static void sdl2_set_scanout_mode(struct sdl2_console *scon, bool scanout)
+{
+    if (scon->scanout_mode == scanout) {
+        return;
+    }
+
+    scon->scanout_mode = scanout;
+    if (!scon->scanout_mode) {
+        if (scon->fbo_id) {
+            glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,
+                                      GL_COLOR_ATTACHMENT0_EXT,
+                                      GL_TEXTURE_2D, 0, 0);
+            glDeleteFramebuffers(1, &scon->fbo_id);
+            glBindFramebuffer(GL_FRAMEBUFFER_EXT, 0);
+            scon->fbo_id = 0;
+        }
+        if (scon->surface) {
+            surface_gl_destroy_texture(scon->gls, scon->surface);
+            surface_gl_create_texture(scon->gls, scon->surface);
+        }
+    }
+}
+
 static void sdl2_gl_render_surface(struct sdl2_console *scon)
 {
     int ww, wh;
 
     SDL_GL_MakeCurrent(scon->real_window, scon->winctx);
+    sdl2_set_scanout_mode(scon, false);
 
     SDL_GetWindowSize(scon->real_window, &ww, &wh);
     surface_gl_setup_viewport(scon->gls, scon->surface, ww, wh);
@@ -110,3 +136,112 @@ void sdl2_gl_redraw(struct sdl2_console *scon)
         sdl2_gl_render_surface(scon);
     }
 }
+
+QEMUGLContext sdl2_gl_create_context(DisplayChangeListener *dcl,
+                                     QEMUGLParams *params)
+{
+    struct sdl2_console *scon = container_of(dcl, struct sdl2_console, dcl);
+    SDL_GLContext ctx;
+
+    assert(scon->opengl);
+
+    SDL_GL_MakeCurrent(scon->real_window, scon->winctx);
+
+    SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK,
+                        SDL_GL_CONTEXT_PROFILE_CORE);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, params->major_ver);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, params->minor_ver);
+
+    ctx = SDL_GL_CreateContext(scon->real_window);
+    return (QEMUGLContext)ctx;
+}
+
+void sdl2_gl_destroy_context(DisplayChangeListener *dcl, QEMUGLContext ctx)
+{
+    SDL_GLContext sdlctx = (SDL_GLContext)ctx;
+
+    SDL_GL_DeleteContext(sdlctx);
+}
+
+int sdl2_gl_make_context_current(DisplayChangeListener *dcl,
+                                 QEMUGLContext ctx)
+{
+    struct sdl2_console *scon = container_of(dcl, struct sdl2_console, dcl);
+    SDL_GLContext sdlctx = (SDL_GLContext)ctx;
+
+    assert(scon->opengl);
+
+    return SDL_GL_MakeCurrent(scon->real_window, sdlctx);
+}
+
+QEMUGLContext sdl2_gl_get_current_context(DisplayChangeListener *dcl)
+{
+    SDL_GLContext sdlctx;
+
+    sdlctx = SDL_GL_GetCurrentContext();
+    return (QEMUGLContext)sdlctx;
+}
+
+void sdl2_gl_scanout(DisplayChangeListener *dcl,
+                     uint32_t backing_id, bool backing_y_0_top,
+                     uint32_t x, uint32_t y,
+                     uint32_t w, uint32_t h)
+{
+    struct sdl2_console *scon = container_of(dcl, struct sdl2_console, dcl);
+
+    assert(scon->opengl);
+    scon->x = x;
+    scon->y = y;
+    scon->w = w;
+    scon->h = h;
+    scon->tex_id = backing_id;
+    scon->y0_top = backing_y_0_top;
+
+    SDL_GL_MakeCurrent(scon->real_window, scon->winctx);
+
+    if (scon->tex_id == 0 || scon->w == 0 || scon->h == 0) {
+        sdl2_set_scanout_mode(scon, false);
+        return;
+    }
+
+    sdl2_set_scanout_mode(scon, true);
+    if (!scon->fbo_id) {
+        glGenFramebuffers(1, &scon->fbo_id);
+    }
+
+    glBindFramebuffer(GL_FRAMEBUFFER_EXT, scon->fbo_id);
+    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
+                              GL_TEXTURE_2D, scon->tex_id, 0);
+}
+
+void sdl2_gl_scanout_flush(DisplayChangeListener *dcl,
+                           uint32_t x, uint32_t y, uint32_t w, uint32_t h)
+{
+    struct sdl2_console *scon = container_of(dcl, struct sdl2_console, dcl);
+    int ww, wh, y1, y2;
+
+    assert(scon->opengl);
+    if (!scon->scanout_mode) {
+        return;
+    }
+    if (!scon->fbo_id) {
+        return;
+    }
+
+    SDL_GL_MakeCurrent(scon->real_window, scon->winctx);
+
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, scon->fbo_id);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+
+    SDL_GetWindowSize(scon->real_window, &ww, &wh);
+    glViewport(0, 0, ww, wh);
+    y1 = scon->y0_top ? 0 : scon->h;
+    y2 = scon->y0_top ? scon->h : 0;
+    glBlitFramebuffer(0, y1, scon->w, y2,
+                      0, 0, ww, wh,
+                      GL_COLOR_BUFFER_BIT, GL_NEAREST);
+    glBindFramebuffer(GL_FRAMEBUFFER_EXT, scon->fbo_id);
+
+    SDL_GL_SwapWindow(scon->real_window);
+}
diff --git a/ui/sdl2.c b/ui/sdl2.c
index cf38df2684..46270f4172 100644
--- a/ui/sdl2.c
+++ b/ui/sdl2.c
@@ -700,6 +700,13 @@ static const DisplayChangeListenerOps dcl_gl_ops = {
     .dpy_refresh             = sdl2_gl_refresh,
     .dpy_mouse_set           = sdl_mouse_warp,
     .dpy_cursor_define       = sdl_mouse_define,
+
+    .dpy_gl_ctx_create       = sdl2_gl_create_context,
+    .dpy_gl_ctx_destroy      = sdl2_gl_destroy_context,
+    .dpy_gl_ctx_make_current = sdl2_gl_make_context_current,
+    .dpy_gl_ctx_get_current  = sdl2_gl_get_current_context,
+    .dpy_gl_scanout          = sdl2_gl_scanout,
+    .dpy_gl_update           = sdl2_gl_scanout_flush,
 };
 #endif