Bug 1594128 - Don't rely on high bits to store the brush_kind varying. r=gw

In GLES the default precision for ints is only 16 bits in the fragment shader.

Differential Revision: https://phabricator.services.mozilla.com/D54000

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

gfx/wr/webrender/res/brush_multi.glsl

@@ -13,14 +13,14 @@
 #define WR_FEATURE_MULTI_BRUSH
 
 // 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             0x3000000
-#define BRUSH_KIND_LINEAR_GRADIENT  0x4000000
-#define BRUSH_KIND_RADIAL_GRADIENT  0x5000000
-#define BRUSH_KIND_BLEND            0x6000000
-#define BRUSH_KIND_MIX_BLEND        0x7000000
-#define BRUSH_KIND_YV               0x8000000
+#define BRUSH_KIND_SOLID            1
+#define BRUSH_KIND_IMAGE            2
+#define BRUSH_KIND_TEXT             3
+#define BRUSH_KIND_LINEAR_GRADIENT  4
+#define BRUSH_KIND_RADIAL_GRADIENT  5
+#define BRUSH_KIND_BLEND            6
+#define BRUSH_KIND_MIX_BLEND        7
+#define BRUSH_KIND_YV               8
 
 int vecs_per_brush(int brush_kind);
 

gfx/wr/webrender/res/prim_shared.glsl

@@ -70,7 +70,7 @@ Instance decode_instance_attributes() {
     instance.segment_index = aData.z & 0xffff;
     instance.flags = aData.z & 0xffff0000;
     instance.resource_address = aData.w & 0xffffff;
-    instance.brush_kind = aData.w & 0xff000000;
+    instance.brush_kind = aData.w >> 24;
 
     return instance;
 }

gfx/wr/webrender/src/gpu_types.rs

@@ -72,15 +72,15 @@ impl ZBufferIdGenerator {
 #[repr(i32)]
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub enum BrushShaderKind {
-    None = 0,
-    Solid           = 0x1000000,
-    Image           = 0x2000000,
-    Text            = 0x3000000,
-    LinearGradient  = 0x4000000,
-    RadialGradient  = 0x5000000,
-    Blend           = 0x6000000,
-    MixBlend        = 0x7000000,
-    Yuv             = 0x8000000,
+    None            = 0,
+    Solid           = 1,
+    Image           = 2,
+    Text            = 3,
+    LinearGradient  = 4,
+    RadialGradient  = 5,
+    Blend           = 6,
+    MixBlend        = 7,
+    Yuv             = 8,
 }
 
 #[derive(Debug, Copy, Clone)]
@@ -368,7 +368,7 @@ impl GlyphInstance {
                 self.prim_header_index.0 as i32,
                 data0,
                 data1,
-                resource_address | BrushShaderKind::Text as i32,
+                resource_address | ((BrushShaderKind::Text as i32) << 24),
             ],
         }
     }
@@ -438,7 +438,7 @@ impl From<BrushInstance> for PrimitiveInstanceData {
                 | ((instance.edge_flags.bits() as i32) << 16)
                 | ((instance.brush_flags.bits() as i32) << 24),
                 instance.resource_address
-                | instance.brush_kind as i32,
+                | ((instance.brush_kind as i32) << 24),
             ]
         }
     }