Revert "Use int when possible to calculate atlas indices in shaders."

This reverts commit 999ec57291dc7cf1d8e3a745627670e6cadc1c12.

Reason for revert: Causing issues with NexusPlayer Vulkan.

Original change's description:
> Use int when possible to calculate atlas indices in shaders.
> 
> On certain iOS devices half has a mantissa of only 10 bits, which is not
> enough to perform the floating point trickery to get the lower bits
> out of the "texture coordinates". Instead we use int if available, and
> float if not available.
> 
> Also re-enables multitexturing for iOS and adds a sample which
> stresses the issue.
> 
> Bug: skia:7285
> Change-Id: I365532c7cbbcca7c7753af209bef46e05be49e11
> Reviewed-on: https://skia-review.googlesource.com/71181
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Jim Van Verth <jvanverth@google.com>

TBR=jvanverth@google.com,bsalomon@google.com,robertphillips@google.com

Change-Id: I82801a73a2a8067588049b213f010ff25f4014f3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:7285
Reviewed-on: https://skia-review.googlesource.com/74001
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

5 files changed, 24 insertions, 66 deletions

diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 69acd15cb2..68cf42ef2a 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -211,12 +211,20 @@ bool GrContext::init(const GrContextOptions& options) {
             new GrDrawingManager(this, prcOptions, atlasTextContextOptions, &fSingleOwner));
 
     GrDrawOpAtlas::AllowMultitexturing allowMultitexturing;
-    if (GrContextOptions::Enable::kNo == options.fAllowMultipleGlyphCacheTextures ||
-        // multitexturing supported only if range can represent the index + texcoords fully
-        !(fCaps->shaderCaps()->floatIs32Bits() || fCaps->shaderCaps()->integerSupport())) {
-        allowMultitexturing = GrDrawOpAtlas::AllowMultitexturing::kNo;
-    } else {
-        allowMultitexturing = GrDrawOpAtlas::AllowMultitexturing::kYes;
+    switch (options.fAllowMultipleGlyphCacheTextures) {
+        case GrContextOptions::Enable::kDefault:
+#ifdef SK_BUILD_FOR_IOS
+            allowMultitexturing = GrDrawOpAtlas::AllowMultitexturing::kNo;
+#else
+            allowMultitexturing = GrDrawOpAtlas::AllowMultitexturing::kYes;
+#endif
+            break;
+        case GrContextOptions::Enable::kNo:
+            allowMultitexturing = GrDrawOpAtlas::AllowMultitexturing::kNo;
+            break;
+        case GrContextOptions::Enable::kYes:
+            allowMultitexturing = GrDrawOpAtlas::AllowMultitexturing::kYes;
+            break;
     }
     fAtlasGlyphCache = new GrAtlasGlyphCache(this, options.fGlyphCacheTextureMaximumBytes,
                                              allowMultitexturing);
diff --git a/src/gpu/effects/GrAtlasedShaderHelpers.h b/src/gpu/effects/GrAtlasedShaderHelpers.h
index 7fc321daa2..ad901411db 100644
--- a/src/gpu/effects/GrAtlasedShaderHelpers.h
+++ b/src/gpu/effects/GrAtlasedShaderHelpers.h
@@ -8,7 +8,6 @@
 #ifndef GrAtlasedShaderHelpers_DEFINED
 #define GrAtlasedShaderHelpers_DEFINED
 
-#include "GrShaderCaps.h"
 #include "glsl/GrGLSLPrimitiveProcessor.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 #include "glsl/GrGLSLVarying.h"
@@ -23,24 +22,17 @@ static void append_index_uv_varyings(GrGLSLPrimitiveProcessor::EmitArgs& args,
     // This extracts the texture index and texel coordinates from the same variable
     // Packing structure: texel coordinates are multiplied by 2 (or shifted left 1)
     //                    texture index is stored as lower bits of both x and y
-    if (args.fShaderCaps->integerSupport()) {
-        args.fVertBuilder->codeAppendf("int2 signedCoords = int2(%s);", inTexCoordsName);
-        args.fVertBuilder->codeAppend("int texIdx = 2*(signedCoords.x & 0x1) + (signedCoords.y & 0x1);");
-        args.fVertBuilder->codeAppend("signedCoords >>= 1;");
-        args.fVertBuilder->codeAppend("float2 intCoords = float2(signedCoords);");
-    } else {
-        args.fVertBuilder->codeAppendf("float2 indexTexCoords = float2(%s.x, %s.y);",
-                                       inTexCoordsName, inTexCoordsName);
-        args.fVertBuilder->codeAppend("float2 intCoords = floor(0.5*indexTexCoords);");
-        args.fVertBuilder->codeAppend("float2 diff = indexTexCoords - 2.0*intCoords;");
-        args.fVertBuilder->codeAppend("float texIdx = 2.0*diff.x + diff.y;");
-    }
+    args.fVertBuilder->codeAppendf("half2 indexTexCoords = half2(%s.x, %s.y);",
+                                   inTexCoordsName, inTexCoordsName);
+    args.fVertBuilder->codeAppend("half2 intCoords = floor(0.5*indexTexCoords);");
+    args.fVertBuilder->codeAppend("half2 diff = indexTexCoords - 2.0*intCoords;");
+    args.fVertBuilder->codeAppend("half texIdx = 2.0*diff.x + diff.y;");
 
     // Multiply by 1/atlasSize to get normalized texture coordinates
     args.fVaryingHandler->addVarying("TextureCoords", uv);
     args.fVertBuilder->codeAppendf("%s = intCoords * %s;", uv->vsOut(), atlasSizeInvName);
 
-    args.fVaryingHandler->addFlatVarying("TexIndex", texIdx);
+    args.fVaryingHandler->addVarying("TexIndex", texIdx);
     args.fVertBuilder->codeAppendf("%s = texIdx;", texIdx->vsOut());
 
     if (st) {
diff --git a/src/gpu/effects/GrBitmapTextGeoProc.cpp b/src/gpu/effects/GrBitmapTextGeoProc.cpp
index 4193f1d24c..d5f930fec4 100644
--- a/src/gpu/effects/GrBitmapTextGeoProc.cpp
+++ b/src/gpu/effects/GrBitmapTextGeoProc.cpp
@@ -38,8 +38,7 @@ public:
                                                           &atlasSizeInvName);
 
         GrGLSLVertToFrag uv(kFloat2_GrSLType);
-        GrSLType texIdxType = args.fShaderCaps->integerSupport() ? kInt_GrSLType : kFloat_GrSLType;
-        GrGLSLVertToFrag texIdx(texIdxType);
+        GrGLSLVertToFrag texIdx(kHalf_GrSLType);
         append_index_uv_varyings(args, btgp.inTextureCoords()->fName, atlasSizeInvName,
                                  &uv, &texIdx, nullptr);
 
diff --git a/src/gpu/effects/GrDistanceFieldGeoProc.cpp b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
index 3e9addef6d..aafabdeb60 100644
--- a/src/gpu/effects/GrDistanceFieldGeoProc.cpp
+++ b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
@@ -78,8 +78,7 @@ public:
 
         // add varyings
         GrGLSLVertToFrag uv(kFloat2_GrSLType);
-        GrSLType texIdxType = args.fShaderCaps->integerSupport() ? kInt_GrSLType : kFloat_GrSLType;
-        GrGLSLVertToFrag texIdx(texIdxType);
+        GrGLSLVertToFrag texIdx(kHalf_GrSLType);
         GrGLSLVertToFrag st(kFloat2_GrSLType);
         append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
                                  &uv, &texIdx, &st);
@@ -345,8 +344,7 @@ public:
                                                           &atlasSizeInvName);
 
         GrGLSLVertToFrag uv(kFloat2_GrSLType);
-        GrSLType texIdxType = args.fShaderCaps->integerSupport() ? kInt_GrSLType : kFloat_GrSLType;
-        GrGLSLVertToFrag texIdx(texIdxType);
+        GrGLSLVertToFrag texIdx(kHalf_GrSLType);
         GrGLSLVertToFrag st(kFloat2_GrSLType);
         append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
                                  &uv, &texIdx, &st);
@@ -641,8 +639,7 @@ public:
 
         // set up varyings
         GrGLSLVertToFrag uv(kFloat2_GrSLType);
-        GrSLType texIdxType = args.fShaderCaps->integerSupport() ? kInt_GrSLType : kFloat_GrSLType;
-        GrGLSLVertToFrag texIdx(texIdxType);
+        GrGLSLVertToFrag texIdx(kHalf_GrSLType);
         GrGLSLVertToFrag st(kFloat2_GrSLType);
         append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
                                  &uv, &texIdx, &st);
diff --git a/src/gpu/text/GrAtlasTextBlobVertexRegenerator.cpp b/src/gpu/text/GrAtlasTextBlobVertexRegenerator.cpp
index 81ae09a6f5..28b2e0f0c0 100644
--- a/src/gpu/text/GrAtlasTextBlobVertexRegenerator.cpp
+++ b/src/gpu/text/GrAtlasTextBlobVertexRegenerator.cpp
@@ -38,9 +38,6 @@ inline void regen_vertices(char* vertex, const GrGlyph* glyph, size_t vertexStri
                            bool useDistanceFields, SkScalar transX, SkScalar transY,
                            GrColor color) {
     uint16_t u0, v0, u1, v1;
-#ifdef DISPLAY_PAGE_INDEX
-    SkColor hackColor;
-#endif
     if (regenTexCoords) {
         SkASSERT(glyph);
         int width = glyph->fBounds.width();
@@ -70,25 +67,6 @@ inline void regen_vertices(char* vertex, const GrGlyph* glyph, size_t vertexStri
         u1 |= uBit;
         v1 <<= 1;
         v1 |= vBit;
-#ifdef DISPLAY_PAGE_INDEX
-        switch (pageIndex) {
-            case 0:
-                hackColor = SK_ColorGREEN;
-                break;
-            case 1:
-                hackColor = SK_ColorRED;
-                break;
-            case 2:
-                hackColor = SK_ColorMAGENTA;
-                break;
-            case 3:
-                hackColor = SK_ColorCYAN;
-                break;
-            default:
-                hackColor = SK_ColorBLACK;
-                break;
-        }
-#endif
     }
 
     // This is a bit wonky, but sometimes we have LCD text, in which case we won't have color
@@ -112,10 +90,6 @@ inline void regen_vertices(char* vertex, const GrGlyph* glyph, size_t vertexStri
         uint16_t* textureCoords = reinterpret_cast<uint16_t*>(vertex + texCoordOffset);
         textureCoords[0] = u0;
         textureCoords[1] = v0;
-#ifdef DISPLAY_PAGE_INDEX
-        SkColor* vcolor = reinterpret_cast<SkColor*>(vertex + colorOffset);
-        *vcolor = hackColor;
-#endif
     }
     vertex += vertexStride;
 
@@ -135,10 +109,6 @@ inline void regen_vertices(char* vertex, const GrGlyph* glyph, size_t vertexStri
         uint16_t* textureCoords = reinterpret_cast<uint16_t*>(vertex + texCoordOffset);
         textureCoords[0] = u0;
         textureCoords[1] = v1;
-#ifdef DISPLAY_PAGE_INDEX
-        SkColor* vcolor = reinterpret_cast<SkColor*>(vertex + colorOffset);
-        *vcolor = hackColor;
-#endif
     }
     vertex += vertexStride;
 
@@ -158,10 +128,6 @@ inline void regen_vertices(char* vertex, const GrGlyph* glyph, size_t vertexStri
         uint16_t* textureCoords = reinterpret_cast<uint16_t*>(vertex + texCoordOffset);
         textureCoords[0] = u1;
         textureCoords[1] = v0;
-#ifdef DISPLAY_PAGE_INDEX
-        SkColor* vcolor = reinterpret_cast<SkColor*>(vertex + colorOffset);
-        *vcolor = hackColor;
-#endif
     }
     vertex += vertexStride;
 
@@ -181,10 +147,6 @@ inline void regen_vertices(char* vertex, const GrGlyph* glyph, size_t vertexStri
         uint16_t* textureCoords = reinterpret_cast<uint16_t*>(vertex + texCoordOffset);
         textureCoords[0] = u1;
         textureCoords[1] = v1;
-#ifdef DISPLAY_PAGE_INDEX
-        SkColor* vcolor = reinterpret_cast<SkColor*>(vertex + colorOffset);
-        *vcolor = hackColor;
-#endif
     }
 }