vkfullscreenquad: support setting blend operations

Allows e.g. blending with an existing image.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2470>

subprojects/gst-plugins-bad/gst-libs/gst/vulkan/gstvkfullscreenquad.c

@@ -57,6 +57,14 @@ struct _GstVulkanFullScreenQuadPrivate
 
   GstVulkanHandle *vert;
   GstVulkanHandle *frag;
+
+  VkBool32 blend_enable;
+  VkBlendFactor src_blend_factor;
+  VkBlendFactor src_alpha_blend_factor;
+  VkBlendFactor dst_blend_factor;
+  VkBlendFactor dst_alpha_blend_factor;
+  VkBlendOp colour_blend_op;
+  VkBlendOp alpha_blend_op;
 };
 
 G_DEFINE_TYPE_WITH_CODE (GstVulkanFullScreenQuad, gst_vulkan_full_screen_quad,
@@ -278,6 +286,7 @@ create_pipeline_layout (GstVulkanFullScreenQuad * self, GError ** error)
 static gboolean
 create_render_pass (GstVulkanFullScreenQuad * self, GError ** error)
 {
+  GstVulkanFullScreenQuadPrivate *priv = GET_PRIV (self);
   VkAttachmentDescription color_attachments[GST_VIDEO_MAX_PLANES];
   VkAttachmentReference color_attachment_refs[GST_VIDEO_MAX_PLANES];
   VkRenderPassCreateInfo render_pass_info;
@@ -468,19 +477,43 @@ create_pipeline (GstVulkanFullScreenQuad * self, GError ** error)
 
   color_blend_attachments[0] = (VkPipelineColorBlendAttachmentState) {
       .colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT,
-      .blendEnable = VK_FALSE
+      .srcColorBlendFactor = priv->src_blend_factor,
+      .dstColorBlendFactor = priv->dst_blend_factor,
+      .colorBlendOp = priv->colour_blend_op,
+      .srcAlphaBlendFactor = priv->src_alpha_blend_factor,
+      .dstAlphaBlendFactor = priv->dst_alpha_blend_factor,
+      .alphaBlendOp = priv->alpha_blend_op,
+      .blendEnable = priv->blend_enable
   };
   color_blend_attachments[1] = (VkPipelineColorBlendAttachmentState) {
       .colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT,
-      .blendEnable = VK_FALSE
+      .srcColorBlendFactor = priv->src_blend_factor,
+      .dstColorBlendFactor = priv->dst_blend_factor,
+      .colorBlendOp = priv->colour_blend_op,
+      .srcAlphaBlendFactor = priv->src_alpha_blend_factor,
+      .dstAlphaBlendFactor = priv->dst_alpha_blend_factor,
+      .alphaBlendOp = priv->alpha_blend_op,
+      .blendEnable = priv->blend_enable
   };
   color_blend_attachments[2] = (VkPipelineColorBlendAttachmentState) {
       .colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT,
-      .blendEnable = VK_FALSE
+      .srcColorBlendFactor = priv->src_blend_factor,
+      .dstColorBlendFactor = priv->dst_blend_factor,
+      .colorBlendOp = priv->colour_blend_op,
+      .srcAlphaBlendFactor = priv->src_alpha_blend_factor,
+      .dstAlphaBlendFactor = priv->dst_alpha_blend_factor,
+      .alphaBlendOp = priv->alpha_blend_op,
+      .blendEnable = priv->blend_enable
   };
   color_blend_attachments[3] = (VkPipelineColorBlendAttachmentState) {
       .colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT,
-      .blendEnable = VK_FALSE
+      .srcColorBlendFactor = priv->src_blend_factor,
+      .dstColorBlendFactor = priv->dst_blend_factor,
+      .colorBlendOp = priv->colour_blend_op,
+      .srcAlphaBlendFactor = priv->src_alpha_blend_factor,
+      .dstAlphaBlendFactor = priv->dst_alpha_blend_factor,
+      .alphaBlendOp = priv->alpha_blend_op,
+      .blendEnable = priv->blend_enable
   };
 
   color_blending = (VkPipelineColorBlendStateCreateInfo) {
@@ -768,7 +801,16 @@ destroy_pipeline (GstVulkanFullScreenQuad * self)
 void
 gst_vulkan_full_screen_quad_init (GstVulkanFullScreenQuad * self)
 {
+  GstVulkanFullScreenQuadPrivate *priv = GET_PRIV (self);
+
   self->trash_list = gst_vulkan_trash_fence_list_new ();
+
+  priv->src_blend_factor = VK_BLEND_FACTOR_ONE;
+  priv->src_alpha_blend_factor = VK_BLEND_FACTOR_ONE;
+  priv->dst_blend_factor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
+  priv->dst_alpha_blend_factor = VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
+  priv->colour_blend_op = VK_BLEND_OP_ADD;
+  priv->alpha_blend_op = VK_BLEND_OP_ADD;
 }
 
 /**
@@ -1182,6 +1224,108 @@ error:
   return FALSE;
 }
 
+/**
+ * gst_vulkan_full_screen_quad_enable_blend:
+ * @self: the #GstVulkanFullScreenQuad
+ * @enable_blend: whether to enable blending
+ *
+ * Enables blending of the input image to the output image.
+ *
+ * See also: gst_vulkan_full_screen_quad_set_blend_operation() and
+ * gst_vulkan_full_screen_quad_set_blend_factors().
+ *
+ * Since: 1.22
+ */
+void
+gst_vulkan_full_screen_quad_enable_blend (GstVulkanFullScreenQuad * self,
+    gboolean enable_blend)
+{
+  GstVulkanFullScreenQuadPrivate *priv;
+
+  g_return_if_fail (GST_IS_VULKAN_FULL_SCREEN_QUAD (self));
+
+  priv = GET_PRIV (self);
+
+  if (priv->blend_enable == VK_TRUE && enable_blend)
+    return;
+  if (priv->blend_enable == VK_FALSE && !enable_blend)
+    return;
+  priv->blend_enable = enable_blend ? VK_TRUE : VK_FALSE;
+
+  clear_graphics_pipeline (self);
+}
+
+/**
+ * gst_vulkan_full_screen_quad_set_blend_factors:
+ * @self: the #GstVulkanFullScreenQuad
+ * @src_blend_factor: the `VkBlendFactor` for the source image for the colour
+ *                    components (RGB)
+ * @src_alpha_blend_factor: the `VkBlendFactor` for the source image for the
+ *                          alpha component.
+ * @dst_blend_factor: the `VkBlendFactor` for the destination image for the
+ *                    colour components (RGB)
+ * @dst_alpha_blend_factor: the `VkBlendFactor` for the destination image for
+ *                          the alpha component.
+ *
+ * You need to enable blend with gst_vulkan_full_screen_quad_enable_blend().
+ *
+ * See also: gst_vulkan_full_screen_quad_set_blend_operation().
+ *
+ * Since: 1.22
+ */
+void
+gst_vulkan_full_screen_quad_set_blend_factors (GstVulkanFullScreenQuad * self,
+    VkBlendFactor src_blend_factor, VkBlendFactor dst_blend_factor,
+    VkBlendFactor src_alpha_blend_factor, VkBlendFactor dst_alpha_blend_factor)
+{
+  GstVulkanFullScreenQuadPrivate *priv;
+
+  g_return_if_fail (GST_IS_VULKAN_FULL_SCREEN_QUAD (self));
+
+  priv = GET_PRIV (self);
+
+  if (priv->src_blend_factor == src_blend_factor
+      && priv->src_alpha_blend_factor == src_alpha_blend_factor
+      && priv->dst_blend_factor == dst_blend_factor
+      && priv->dst_alpha_blend_factor == dst_alpha_blend_factor)
+    return;
+
+  priv->src_blend_factor = src_blend_factor;
+  priv->src_alpha_blend_factor = src_alpha_blend_factor;
+  priv->dst_blend_factor = dst_blend_factor;
+  priv->dst_alpha_blend_factor = dst_alpha_blend_factor;
+
+  clear_graphics_pipeline (self);
+}
+
+/**
+ * gst_vulkan_full_screen_quad_set_blend_operation:
+ * @self: the #GstVulkanFullScreenQuad
+ * @colour_blend_op: the `VkBlendOp` to use for blending colour (RGB) values
+ * @alpha_blend_op: the `VkBlendOp` to use for blending alpha values
+ *
+ * You need to enable blend with gst_vulkan_full_screen_quad_enable_blend().
+ *
+ * See also: gst_vulkan_full_screen_quad_set_blend_factors().
+ *
+ * Since: 1.22
+ */
+void
+gst_vulkan_full_screen_quad_set_blend_operation (GstVulkanFullScreenQuad * self,
+    VkBlendOp colour_blend_op, VkBlendOp alpha_blend_op)
+{
+  GstVulkanFullScreenQuadPrivate *priv;
+
+  g_return_if_fail (GST_IS_VULKAN_FULL_SCREEN_QUAD (self));
+
+  priv = GET_PRIV (self);
+
+  priv->colour_blend_op = colour_blend_op;
+  priv->alpha_blend_op = alpha_blend_op;
+
+  clear_graphics_pipeline (self);
+}
+
 /**
  * gst_vulkan_full_screen_quad_prepare_draw:
  * @self: the #GstVulkanFullScreenQuad

subprojects/gst-plugins-bad/gst-libs/gst/vulkan/gstvkfullscreenquad.h

@@ -119,6 +119,19 @@ GST_VULKAN_API
 gboolean            gst_vulkan_full_screen_quad_set_input_buffer    (GstVulkanFullScreenQuad * self, GstBuffer * buffer, GError ** error);
 GST_VULKAN_API
 gboolean            gst_vulkan_full_screen_quad_set_output_buffer   (GstVulkanFullScreenQuad * self, GstBuffer * buffer, GError ** error);
+GST_VULKAN_API
+void                gst_vulkan_full_screen_quad_enable_blend        (GstVulkanFullScreenQuad * self,
+                                                                     gboolean enable_blend);
+GST_VULKAN_API
+void                gst_vulkan_full_screen_quad_set_blend_operation (GstVulkanFullScreenQuad * self,
+                                                                     VkBlendOp colour_blend_op,
+                                                                     VkBlendOp alpha_blend_op);
+GST_VULKAN_API
+void                gst_vulkan_full_screen_quad_set_blend_factors   (GstVulkanFullScreenQuad * self,
+                                                                     VkBlendFactor src_blend_factor,
+                                                                     VkBlendFactor dst_blend_factor,
+                                                                     VkBlendFactor src_alpha_blend_factor,
+                                                                     VkBlendFactor dst_alpha_blend_factor);
 
 GST_VULKAN_API
 gboolean            gst_vulkan_full_screen_quad_prepare_draw        (GstVulkanFullScreenQuad * self, GstVulkanFence * fence, GError ** error);