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gl/overlaycompositor: support both (un)premultiplied alpha

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Using the correct blend modes for each case or converting to
premultipled in the very unlikely case that separate blend modes are
unavailable on ancient opengl hardware.
This commit is contained in:
Matthew Waters 2018-10-04 23:02:05 +10:00
parent 5a3666395e
commit 2315936561
1 changed files with 30 additions and 4 deletions
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34
gst-libs/gst/gl/gstgloverlaycompositor.c
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@ -349,10 +349,26 @@ gst_gl_composition_overlay_upload (GstGLCompositionOverlay * overlay,
GstVideoMeta *vmeta;
GstVideoFrame *comp_frame;
GstVideoFrame gl_frame;
GstVideoOverlayFormatFlags flags;
GstVideoOverlayFormatFlags alpha_flags;
flags = gst_video_overlay_rectangle_get_flags (overlay->rectangle);
flags = 0;
if (flags & GST_VIDEO_OVERLAY_FORMAT_FLAG_PREMULTIPLIED_ALPHA) {
alpha_flags = GST_VIDEO_OVERLAY_FORMAT_FLAG_PREMULTIPLIED_ALPHA;
} else if (!overlay->context->gl_vtable->BlendFuncSeparate) {
GST_FIXME_OBJECT (overlay, "No separate blend mode function, "
"cannot perform correct blending of unmultipled alpha in OpenGL. "
"Software converting");
alpha_flags = GST_VIDEO_OVERLAY_FORMAT_FLAG_PREMULTIPLIED_ALPHA;
} else {
alpha_flags = 0;
}
comp_buffer =
gst_video_overlay_rectangle_get_pixels_unscaled_argb (overlay->rectangle,
GST_VIDEO_OVERLAY_FORMAT_FLAG_PREMULTIPLIED_ALPHA);
alpha_flags);
comp_frame = g_slice_new (GstVideoFrame);
@ -448,8 +464,7 @@ enum
#define DEFAULT_YINVERT FALSE
G_DEFINE_TYPE_WITH_CODE (GstGLOverlayCompositor, gst_gl_overlay_compositor,
GST_TYPE_OBJECT, G_ADD_PRIVATE (GstGLOverlayCompositor);
DEBUG_INIT);
GST_TYPE_OBJECT, G_ADD_PRIVATE (GstGLOverlayCompositor); DEBUG_INIT);
static void gst_gl_overlay_compositor_finalize (GObject * object);
static void gst_gl_overlay_compositor_set_property (GObject * object,
@ -692,7 +707,6 @@ gst_gl_overlay_compositor_draw_overlays (GstGLOverlayCompositor * compositor)
GList *l;
gl->Enable (GL_BLEND);
gl->BlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
gst_gl_shader_use (compositor->shader);
gl->ActiveTexture (GL_TEXTURE0);
@ -700,6 +714,18 @@ gst_gl_overlay_compositor_draw_overlays (GstGLOverlayCompositor * compositor)
for (l = compositor->overlays; l != NULL; l = l->next) {
GstGLCompositionOverlay *overlay = (GstGLCompositionOverlay *) l->data;
GstVideoOverlayFormatFlags flags;
flags = gst_video_overlay_rectangle_get_flags (overlay->rectangle);
flags = 0;
if (flags & GST_VIDEO_OVERLAY_FORMAT_FLAG_PREMULTIPLIED_ALPHA
|| !gl->BlendFuncSeparate) {
gl->BlendFunc (GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
} else {
gl->BlendFuncSeparate (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE,
GL_ONE_MINUS_SRC_ALPHA);
}
gst_gl_composition_overlay_draw (overlay, compositor->shader);
}