Bug 1594128 - Encode the brush shader type in the instance attributes. r=gw

This will allow the upcoming super-brush shader to select its behavior at runtime.

Differential Revision: https://phabricator.services.mozilla.com/D53724

--HG--
extra : moz-landing-system : lando

gfx/wr/webrender/res/brush.glsl

@@ -72,6 +72,11 @@ void brush_vs(
 
 #define INVALID_SEGMENT_INDEX                   0xffff
 
+// These constants must match the BrushShaderKind enum in gpu_types.rs.
+#define BRUSH_KIND_SOLID 0x1000000
+#define BRUSH_KIND_IMAGE 0x2000000
+#define BRUSH_KIND_TEXT  0x4000000
+
 void main(void) {
     // Load the brush instance from vertex attributes.
     Instance instance = decode_instance_attributes();
@@ -158,7 +163,7 @@ void main(void) {
         ph.local_rect,
         segment_rect,
         ph.user_data,
-        instance.user_data,
+        instance.resource_address,
         transform.m,
         pic_task,
         brush_flags,

gfx/wr/webrender/res/prim_shared.glsl

@@ -57,7 +57,8 @@ struct Instance
     int clip_address;
     int segment_index;
     int flags;
-    int user_data;
+    int resource_address;
+    int brush_kind;
 };
 
 Instance decode_instance_attributes() {
@@ -68,7 +69,8 @@ Instance decode_instance_attributes() {
     instance.clip_address = aData.y & 0xffff;
     instance.segment_index = aData.z & 0xffff;
     instance.flags = aData.z & 0xffff0000;
-    instance.user_data = aData.w;
+    instance.resource_address = aData.w & 0xffffff;
+    instance.brush_kind = aData.w & 0xff000000;
 
     return instance;
 }

gfx/wr/webrender/res/ps_text_run.glsl

@@ -178,7 +178,6 @@ void main(void) {
     int glyph_index = instance.segment_index;
     int subpx_dir = (instance.flags >> 24) & 0xff;
     int color_mode = (instance.flags >> 16) & 0xff;
-    int resource_address = instance.user_data;
 
     PrimitiveHeader ph = fetch_prim_header(instance.prim_header_address);
     Transform transform = fetch_transform(ph.transform_id);
@@ -195,7 +194,7 @@ void main(void) {
     Glyph glyph = fetch_glyph(ph.specific_prim_address, glyph_index);
     glyph.offset += ph.local_rect.p0 - text_offset;
 
-    GlyphResource res = fetch_glyph_resource(resource_address);
+    GlyphResource res = fetch_glyph_resource(instance.resource_address);
 
 #ifdef WR_FEATURE_GLYPH_TRANSFORM
     // Transform from local space to glyph space.

gfx/wr/webrender/src/batch.rs

@@ -11,7 +11,7 @@ use crate::composite::{CompositeState, CompositeTile, CompositeTileSurface};
 use crate::glyph_rasterizer::GlyphFormat;
 use crate::gpu_cache::{GpuBlockData, GpuCache, GpuCacheHandle, GpuCacheAddress};
 use crate::gpu_types::{BrushFlags, BrushInstance, PrimitiveHeaders, ZBufferId, ZBufferIdGenerator};
-use crate::gpu_types::{ClipMaskInstance, SplitCompositeInstance};
+use crate::gpu_types::{ClipMaskInstance, SplitCompositeInstance, BrushShaderKind};
 use crate::gpu_types::{PrimitiveInstanceData, RasterizationSpace, GlyphInstance};
 use crate::gpu_types::{PrimitiveHeader, PrimitiveHeaderIndex, TransformPaletteId, TransformPalette};
 use crate::internal_types::{FastHashMap, SavedTargetIndex, Swizzle, TextureSource, Filter};
@@ -70,6 +70,17 @@ pub enum BatchKind {
     Brush(BrushBatchKind),
 }
 
+impl BatchKind {
+    fn shader_kind(&self) -> BrushShaderKind {
+        match self {
+            BatchKind::Brush(BrushBatchKind::Solid) => BrushShaderKind::Solid,
+            BatchKind::Brush(BrushBatchKind::Image(..)) => BrushShaderKind::Image,
+            BatchKind::TextRun(..) => BrushShaderKind::Text,
+            _ => BrushShaderKind::None,
+        }
+    }
+}
+
 /// Optional textures that can be used as a source in the shaders.
 /// Textures that are not used by the batch are equal to TextureId::invalid().
 #[derive(Copy, Clone, Debug)]
@@ -575,7 +586,7 @@ impl BatchBuilder {
         clip_task_address: RenderTaskAddress,
         brush_flags: BrushFlags,
         prim_header_index: PrimitiveHeaderIndex,
-        user_data: i32,
+        resource_address: i32,
         prim_vis_mask: PrimitiveVisibilityMask,
     ) {
         for batcher in &mut self.batchers {
@@ -589,7 +600,8 @@ impl BatchBuilder {
                     render_task_address,
                     brush_flags,
                     prim_header_index,
-                    user_data,
+                    resource_address,
+                    brush_kind: batch_key.kind.shader_kind(),
                 };
 
                 batcher.push_single_instance(

gfx/wr/webrender/src/gpu_types.rs

@@ -63,6 +63,21 @@ impl ZBufferIdGenerator {
     }
 }
 
+/// A shader kind identifier that can be used by a generic-shader to select the behavior at runtime.
+///
+/// Not all brush kinds need to be present in this enum, only those we want to support in the generic
+/// brush shader.
+/// Do not use the 24 lowest bits. This will be packed with other information in the vertex attributes.
+/// The constants must match the corresponding defines in brush.glsl.
+#[repr(i32)]
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub enum BrushShaderKind {
+    None = 0,
+    Solid = 0x1000000,
+    Image = 0x2000000,
+    Text = 0x4000000,
+}
+
 #[derive(Debug, Copy, Clone)]
 #[cfg_attr(feature = "capture", derive(Serialize))]
 #[cfg_attr(feature = "replay", derive(Deserialize))]
@@ -342,13 +357,13 @@ impl GlyphInstance {
     // TODO(gw): Some of these fields can be moved to the primitive
     //           header since they are constant, and some can be
     //           compressed to a smaller size.
-    pub fn build(&self, data0: i32, data1: i32, data2: i32) -> PrimitiveInstanceData {
+    pub fn build(&self, data0: i32, data1: i32, resource_address: i32) -> PrimitiveInstanceData {
         PrimitiveInstanceData {
             data: [
                 self.prim_header_index.0 as i32,
                 data0,
                 data1,
-                data2,
+                resource_address | BrushShaderKind::Text as i32,
             ],
         }
     }
@@ -395,10 +410,7 @@ bitflags! {
     }
 }
 
-// TODO(gw): Some of these fields can be moved to the primitive
-//           header since they are constant, and some can be
-//           compressed to a smaller size.
-#[repr(C)]
+/// Convenience structure to encode into PrimitiveInstanceData.
 pub struct BrushInstance {
     pub prim_header_index: PrimitiveHeaderIndex,
     pub render_task_address: RenderTaskAddress,
@@ -406,7 +418,8 @@ pub struct BrushInstance {
     pub segment_index: i32,
     pub edge_flags: EdgeAaSegmentMask,
     pub brush_flags: BrushFlags,
-    pub user_data: i32,
+    pub resource_address: i32,
+    pub brush_kind: BrushShaderKind,
 }
 
 impl From<BrushInstance> for PrimitiveInstanceData {
@@ -414,12 +427,13 @@ impl From<BrushInstance> for PrimitiveInstanceData {
         PrimitiveInstanceData {
             data: [
                 instance.prim_header_index.0,
-                ((instance.render_task_address.0 as i32) << 16) |
-                instance.clip_task_address.0 as i32,
-                instance.segment_index |
-                ((instance.edge_flags.bits() as i32) << 16) |
-                ((instance.brush_flags.bits() as i32) << 24),
-                instance.user_data,
+                ((instance.render_task_address.0 as i32) << 16)
+                | instance.clip_task_address.0 as i32,
+                instance.segment_index
+                | ((instance.edge_flags.bits() as i32) << 16)
+                | ((instance.brush_flags.bits() as i32) << 24),
+                instance.resource_address
+                | instance.brush_kind as i32,
             ]
         }
     }