[2D,Metal]: Fix subpixel blending; fix inconsistent blend state in Metal

drivers/metal/metal_objects.h

@@ -318,6 +318,13 @@ public:
 			dirty.set_flag(DirtyFlag::DIRTY_UNIFORMS);
 		}
 
+		_FORCE_INLINE_ void mark_blend_dirty() {
+			if (!blend_constants.has_value()) {
+				return;
+			}
+			dirty.set_flag(DirtyFlag::DIRTY_BLEND);
+		}
+
 		MTLScissorRect clip_to_render_area(MTLScissorRect p_rect) const {
 			uint32_t raLeft = render_area.position.x;
 			uint32_t raRight = raLeft + render_area.size.width;

drivers/metal/metal_objects.mm

@@ -143,6 +143,9 @@ void MDCommandBuffer::bind_pipeline(RDD::PipelineID p_pipeline) {
 			if (render.pipeline != nullptr && render.pipeline->depth_stencil != rp->depth_stencil) {
 				render.dirty.set_flag(RenderState::DIRTY_DEPTH);
 			}
+			if (rp->raster_state.blend.enabled) {
+				render.dirty.set_flag(RenderState::DIRTY_BLEND);
+			}
 			render.pipeline = rp;
 		}
 	} else if (p->type == MDPipelineType::Compute) {
@@ -301,6 +304,7 @@ void MDCommandBuffer::render_clear_attachments(VectorView<RDD::AttachmentClear>
 	render.mark_viewport_dirty();
 	render.mark_scissors_dirty();
 	render.mark_vertex_dirty();
+	render.mark_blend_dirty();
 }
 
 void MDCommandBuffer::_render_set_dirty_state() {

servers/rendering/renderer_rd/renderer_canvas_render_rd.cpp

@@ -2479,6 +2479,7 @@ void RendererCanvasRenderRD::_record_item_commands(const Item *p_item, RenderTar
 					r_current_batch = _new_batch(r_batch_broken);
 					r_current_batch->command_type = Item::Command::TYPE_NINEPATCH;
 					r_current_batch->command = c;
+					r_current_batch->has_blend = false;
 					r_current_batch->pipeline_variant = PipelineVariant::PIPELINE_VARIANT_NINEPATCH;
 				}
 
@@ -2548,6 +2549,7 @@ void RendererCanvasRenderRD::_record_item_commands(const Item *p_item, RenderTar
 				r_current_batch = _new_batch(r_batch_broken);
 
 				r_current_batch->command_type = Item::Command::TYPE_POLYGON;
+				r_current_batch->has_blend = false;
 				r_current_batch->command = c;
 
 				TextureState tex_state(polygon->texture, texture_filter, texture_repeat, false, use_linear_colors);
@@ -2585,6 +2587,7 @@ void RendererCanvasRenderRD::_record_item_commands(const Item *p_item, RenderTar
 				if (primitive->point_count != r_current_batch->primitive_points || r_current_batch->command_type != Item::Command::TYPE_PRIMITIVE) {
 					r_current_batch = _new_batch(r_batch_broken);
 					r_current_batch->command_type = Item::Command::TYPE_PRIMITIVE;
+					r_current_batch->has_blend = false;
 					r_current_batch->command = c;
 					r_current_batch->primitive_points = primitive->point_count;
 
@@ -2646,6 +2649,7 @@ void RendererCanvasRenderRD::_record_item_commands(const Item *p_item, RenderTar
 				r_current_batch = _new_batch(r_batch_broken);
 				r_current_batch->command = c;
 				r_current_batch->command_type = c->type;
+				r_current_batch->has_blend = false;
 
 				InstanceData *instance_data = nullptr;
 
@@ -2799,6 +2803,7 @@ void RendererCanvasRenderRD::_render_batch(RD::DrawListID p_draw_list, PipelineV
 			RID pipeline = p_pipeline_variants->variants[p_batch->light_mode][p_batch->pipeline_variant].get_render_pipeline(RD::INVALID_ID, p_framebuffer_format);
 			RD::get_singleton()->draw_list_bind_render_pipeline(p_draw_list, pipeline);
 			if (p_batch->has_blend) {
+				DEV_ASSERT(p_batch->pipeline_variant == PIPELINE_VARIANT_QUAD_LCD_BLEND);
 				RD::get_singleton()->draw_list_set_blend_constants(p_draw_list, p_batch->modulate);
 			}