Tweak pointlight3d sample to work in Raster backend

- Once we add all the missing intrinsics, the locally defined ones
  can go away.
- Having the default interpreter vector width match the raster pipeline
  is a huge perf win.

Change-Id: I482e409e57791b78a0e6fb15929ae77eb0e76bf3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/265600
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

Author: brianosman

samplecode/Sample3D.cpp

@@ -338,13 +338,22 @@ class SamplePointLight3D : public Sample3DView {
             uniform float4x4 localToWorld;
             uniform float3   lightPos;
 
+            // TODO: Remove these helpers once all intrinsics work on the raster backend
+            float3 normalize_(float3 v) {
+                return v / sqrt(dot(v, v));
+            }
+
+            float max_(float a, float b) {
+                return a > b ? a : b;
+            }
+
             void main(float x, float y, inout half4 color) {
                 float3 plane_pos = (localToWorld * float4(x, y, 0, 1)).xyz;
-                float3 plane_norm = normalize((localToWorld * float4(0, 0, 1, 0)).xyz);
-                float3 light_dir = normalize(lightPos - plane_pos);
+                float3 plane_norm = normalize_((localToWorld * float4(0, 0, 1, 0)).xyz);
+                float3 light_dir = normalize_(lightPos - plane_pos);
                 float ambient = 0.5;
                 float dp = dot(plane_norm, light_dir);
-                float scale = ambient + max(dp, 0);
+                float scale = ambient + max_(dp, 0);
 
                 color = color * half4(float4(scale, scale, scale, 1));
             }

src/sksl/SkSLByteCode.h

@@ -220,7 +220,7 @@ enum class TypeCategory {
 
 class SK_API ByteCode {
 public:
-    static constexpr int kVecWidth = 16;
+    static constexpr int kVecWidth = 8;
 
     ByteCode() = default;