vo_opengl: support framebuffer invalidation

Not sure how much can be gained with this, as we can't use it properly
yet. For now, this is used only before rendering, which probably does
overwhelmingly nothing.

In the future, this should be used after temporary passes, which could
possibly reduce memory usage and even memory bandwidth usage, depending
on the drivers.

4 files changed, 26 insertions, 0 deletions

diff --git a/video/out/opengl/common.c b/video/out/opengl/common.c
index ed3acede1c..16a5018dfd 100644
--- a/video/out/opengl/common.c
+++ b/video/out/opengl/common.c
@@ -269,6 +269,14 @@ static const struct gl_functions gl_functions[] = {
             {0}
         },
     },
+    {
+        .ver_core = 430,
+        .ver_es_core = 300,
+        .functions = (const struct gl_function[]) {
+            DEF_FN(InvalidateFramebuffer),
+            {0}
+        },
+    },
     // Swap control, always an OS specific extension
     // The OSX code loads this manually.
     {
diff --git a/video/out/opengl/common.h b/video/out/opengl/common.h
index 4f21e25455..4ee61975f4 100644
--- a/video/out/opengl/common.h
+++ b/video/out/opengl/common.h
@@ -181,6 +181,8 @@ struct GL {
     void (GLAPIENTRY *UniformMatrix3fv)(GLint, GLsizei, GLboolean,
                                         const GLfloat *);
 
+    void (GLAPIENTRY *InvalidateFramebuffer)(GLenum, GLsizei, const GLenum *);
+
     GLsync (GLAPIENTRY *FenceSync)(GLenum, GLbitfield);
     GLenum (GLAPIENTRY *ClientWaitSync)(GLsync, GLbitfield, GLuint64);
     void (GLAPIENTRY *DeleteSync)(GLsync sync);
diff --git a/video/out/opengl/utils.c b/video/out/opengl/utils.c
index 199895e4ec..f8ed6eebaf 100644
--- a/video/out/opengl/utils.c
+++ b/video/out/opengl/utils.c
@@ -293,6 +293,7 @@ bool fbotex_change(struct fbotex *fbo, GL *gl, struct mp_log *log, int w, int h,
     if (fbo->rw == cw && fbo->rh == ch && fbo->iformat == iformat) {
         fbo->lw = w;
         fbo->lh = h;
+        fbotex_invalidate(fbo);
         return true;
     }
 
@@ -378,6 +379,20 @@ void fbotex_uninit(struct fbotex *fbo)
     }
 }
 
+// Mark framebuffer contents as unneeded.
+void fbotex_invalidate(struct fbotex *fbo)
+{
+    GL *gl = fbo->gl;
+
+    if (!fbo->fbo || !gl->InvalidateFramebuffer)
+        return;
+
+    gl->BindFramebuffer(GL_FRAMEBUFFER, fbo->fbo);
+    gl->InvalidateFramebuffer(GL_FRAMEBUFFER, 1,
+                              (GLenum[]){GL_COLOR_ATTACHMENT0});
+    gl->BindFramebuffer(GL_FRAMEBUFFER, 0);
+}
+
 // Standard parallel 2D projection, except y1 < y0 means that the coordinate
 // system is flipped, not the projection.
 void gl_transform_ortho(struct gl_transform *t, float x0, float x1,
diff --git a/video/out/opengl/utils.h b/video/out/opengl/utils.h
index c7a72969f6..569ec0f23c 100644
--- a/video/out/opengl/utils.h
+++ b/video/out/opengl/utils.h
@@ -84,6 +84,7 @@ bool fbotex_change(struct fbotex *fbo, GL *gl, struct mp_log *log, int w, int h,
 #define FBOTEX_FUZZY_H 2
 #define FBOTEX_FUZZY (FBOTEX_FUZZY_W | FBOTEX_FUZZY_H)
 void fbotex_set_filter(struct fbotex *fbo, GLenum gl_filter);
+void fbotex_invalidate(struct fbotex *fbo);
 
 // A 3x2 matrix, with the translation part separate.
 struct gl_transform {