Add multitexture support to text and path shaders, take 3.

This does not add additional textures to the atlases, just adds the
ability to access those textures in the shaders.

Bug: skia:3550
Change-Id: I4c1da2bc374a76131f5f4ad946543e03e0ab3126
Reviewed-on: https://skia-review.googlesource.com/44841
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

3 files changed, 117 insertions, 73 deletions

diff --git a/src/gpu/effects/GrAtlasedShaderHelpers.h b/src/gpu/effects/GrAtlasedShaderHelpers.h
new file mode 100644
index 0000000000..67f2c242c2
--- /dev/null
+++ b/src/gpu/effects/GrAtlasedShaderHelpers.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrAtlasedShaderHelpers_DEFINED
+#define GrAtlasedShaderHelpers_DEFINED
+
+#include "glsl/GrGLSLPrimitiveProcessor.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "glsl/GrGLSLVarying.h"
+#include "glsl/GrGLSLVertexShaderBuilder.h"
+
+static void append_index_uv_varyings(GrGLSLPrimitiveProcessor::EmitArgs& args,
+                                     const char* inTexCoordsName,
+                                     const char* atlasSizeInvName,
+                                     GrGLSLVertToFrag *uv,
+                                     GrGLSLVertToFrag *texIdx,
+                                     GrGLSLVertToFrag *st) {
+    // 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
+    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;");
+
+    // Multiply by 1/atlasSize to get normalized texture coordinates
+    args.fVaryingHandler->addVarying("TextureCoords", uv, kHigh_GrSLPrecision);
+    args.fVertBuilder->codeAppendf("%s = intCoords * %s;", uv->vsOut(), atlasSizeInvName);
+
+    args.fVaryingHandler->addVarying("TexIndex", texIdx);
+    args.fVertBuilder->codeAppendf("%s = texIdx;", texIdx->vsOut());
+
+    if (st) {
+        args.fVaryingHandler->addVarying("IntTextureCoords", st, kHigh_GrSLPrecision);
+        args.fVertBuilder->codeAppendf("%s = intCoords;", st->vsOut());
+    }
+}
+
+static void append_multitexture_lookup(GrGLSLPrimitiveProcessor::EmitArgs& args,
+                                       int numTextureSamplers,
+                                       const GrGLSLVertToFrag &texIdx,
+                                       const char* coordName,
+                                       const char* colorName) {
+    // conditionally load from the indexed texture sampler
+    if (numTextureSamplers > 1) {
+        args.fFragBuilder->codeAppendf("if (%s == 0) ", texIdx.fsIn());
+    }
+    args.fFragBuilder->codeAppendf("{ %s = ", colorName);
+    args.fFragBuilder->appendTextureLookup(args.fTexSamplers[0], coordName, kVec2f_GrSLType);
+    args.fFragBuilder->codeAppend("; }");
+    for (int i = 1; i < numTextureSamplers; ++i) {
+        args.fFragBuilder->codeAppendf("else if (%s == %d) { %s =", texIdx.fsIn(), i, colorName);
+        args.fFragBuilder->appendTextureLookup(args.fTexSamplers[i], coordName, kVec2f_GrSLType);
+        args.fFragBuilder->codeAppend("; }");
+    }
+}
+
+#endif
diff --git a/src/gpu/effects/GrBitmapTextGeoProc.cpp b/src/gpu/effects/GrBitmapTextGeoProc.cpp
index c2cf8ebc22..8013d2e4b8 100644
--- a/src/gpu/effects/GrBitmapTextGeoProc.cpp
+++ b/src/gpu/effects/GrBitmapTextGeoProc.cpp
@@ -7,6 +7,7 @@
 
 #include "GrBitmapTextGeoProc.h"
 
+#include "GrAtlasedShaderHelpers.h"
 #include "GrTexture.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 #include "glsl/GrGLSLGeometryProcessor.h"
@@ -36,12 +37,10 @@ public:
                                                           "AtlasSizeInv",
                                                           &atlasSizeInvName);
 
-        GrGLSLVertToFrag v(kVec2f_GrSLType);
-        varyingHandler->addVarying("TextureCoords", &v, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y) * %s;", v.vsOut(),
-                                 btgp.inTextureCoords()->fName,
-                                 btgp.inTextureCoords()->fName,
-                                 atlasSizeInvName);
+        GrGLSLVertToFrag uv(kVec2f_GrSLType);
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
+        append_index_uv_varyings(args, btgp.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &texIdx, nullptr);
 
         GrGLSLPPFragmentBuilder* fragBuilder = args.fFragBuilder;
         // Setup pass through color
@@ -64,18 +63,16 @@ public:
                              btgp.localMatrix(),
                              args.fFPCoordTransformHandler);
 
+        fragBuilder->codeAppend("float4 texColor;");
+        append_multitexture_lookup(args, btgp.numTextureSamplers(),
+                                   texIdx, uv.fsIn(), "texColor");
+
         if (btgp.maskFormat() == kARGB_GrMaskFormat) {
-            fragBuilder->codeAppendf("%s = ", args.fOutputColor);
-            fragBuilder->appendTextureLookupAndModulate(args.fOutputColor,
-                                                        args.fTexSamplers[0],
-                                                        v.fsIn(),
-                                                        kVec2f_GrSLType);
-            fragBuilder->codeAppend(";");
+            // modulate by color
+            fragBuilder->codeAppendf("%s = %s * texColor;", args.fOutputColor, args.fOutputColor);
             fragBuilder->codeAppendf("%s = float4(1);", args.fOutputCoverage);
         } else {
-            fragBuilder->codeAppendf("%s = ", args.fOutputCoverage);
-            fragBuilder->appendTextureLookup(args.fTexSamplers[0], v.fsIn(), kVec2f_GrSLType);
-            fragBuilder->codeAppend(";");
+            fragBuilder->codeAppendf("%s = texColor;", args.fOutputCoverage);
         }
     }
 
@@ -89,7 +86,7 @@ public:
             fColor = btgp.color();
         }
 
-        SkASSERT(btgp.numTextureSamplers() == 1);
+        SkASSERT(btgp.numTextureSamplers() >= 1);
         GrTexture* atlas = btgp.textureSampler(0).peekTexture();
         SkASSERT(atlas && SkIsPow2(atlas->width()) && SkIsPow2(atlas->height()));
 
@@ -108,6 +105,7 @@ public:
         key |= (btgp.usesLocalCoords() && btgp.localMatrix().hasPerspective()) ? 0x1 : 0x0;
         key |= btgp.maskFormat() << 1;
         b->add32(key);
+        b->add32(btgp.numTextureSamplers());
     }
 
 private:
diff --git a/src/gpu/effects/GrDistanceFieldGeoProc.cpp b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
index 81b33262da..953d4cc2bc 100644
--- a/src/gpu/effects/GrDistanceFieldGeoProc.cpp
+++ b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
@@ -7,6 +7,7 @@
 
 #include "GrDistanceFieldGeoProc.h"
 
+#include "GrAtlasedShaderHelpers.h"
 #include "GrTexture.h"
 #include "SkDistanceFieldGen.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
@@ -78,17 +79,10 @@ public:
 
         // add varyings
         GrGLSLVertToFrag uv(kVec2f_GrSLType);
-        varyingHandler->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y) * %s;", uv.vsOut(),
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 atlasSizeInvName);
-
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
         GrGLSLVertToFrag st(kVec2f_GrSLType);
-        varyingHandler->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y);", st.vsOut(),
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 dfTexEffect.inTextureCoords()->fName);
+        append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &texIdx, &st);
 
         bool isUniformScale = (dfTexEffect.getFlags() & kUniformScale_DistanceFieldEffectMask) ==
                               kUniformScale_DistanceFieldEffectMask;
@@ -100,12 +94,12 @@ public:
 
         // Use highp to work around aliasing issues
         fragBuilder->codeAppendf("highp float2 uv = %s;\n", uv.fsIn());
+        fragBuilder->codeAppend("float4 texColor;");
+        append_multitexture_lookup(args, dfTexEffect.numTextureSamplers(),
+                                   texIdx, "uv", "texColor");
 
-        fragBuilder->codeAppend("float texColor = ");
-        fragBuilder->appendTextureLookup(args.fTexSamplers[0], "uv", kVec2f_GrSLType);
-        fragBuilder->codeAppend(".r;");
         fragBuilder->codeAppend("float distance = "
-                       SK_DistanceFieldMultiplier "*(texColor - " SK_DistanceFieldThreshold ");");
+                      SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");");
 #ifdef SK_GAMMA_APPLY_TO_A8
         // adjust width based on gamma
         fragBuilder->codeAppendf("distance -= %s;", distanceAdjustUniName);
@@ -197,7 +191,7 @@ public:
             pdman.setMatrix3f(fViewMatrixUniform, viewMatrix);
         }
 
-        SkASSERT(dfa8gp.numTextureSamplers() == 1);
+        SkASSERT(dfa8gp.numTextureSamplers() >= 1);
         GrTexture* atlas = dfa8gp.textureSampler(0).peekTexture();
         SkASSERT(atlas && SkIsPow2(atlas->width()) && SkIsPow2(atlas->height()));
 
@@ -216,6 +210,7 @@ public:
         uint32_t key = dfTexEffect.getFlags();
         key |= ComputePosKey(dfTexEffect.viewMatrix()) << 16;
         b->add32(key);
+        b->add32(dfTexEffect.numTextureSamplers());
     }
 
 private:
@@ -332,17 +327,10 @@ public:
                                                           &atlasSizeInvName);
 
         GrGLSLVertToFrag uv(kVec2f_GrSLType);
-        varyingHandler->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y) * %s;", uv.vsOut(),
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 atlasSizeInvName);
-
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
         GrGLSLVertToFrag st(kVec2f_GrSLType);
-        varyingHandler->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y);", st.vsOut(),
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 dfTexEffect.inTextureCoords()->fName);
+        append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &texIdx, &st);
 
         // setup pass through color
         varyingHandler->addPassThroughAttribute(dfTexEffect.inColor(), args.fOutputColor);
@@ -365,12 +353,12 @@ public:
 
         // Use highp to work around aliasing issues
         fragBuilder->codeAppendf("highp float2 uv = %s;", uv.fsIn());
+        fragBuilder->codeAppend("float4 texColor;");
+        append_multitexture_lookup(args, dfTexEffect.numTextureSamplers(),
+                                   texIdx, "uv", "texColor");
 
-        fragBuilder->codeAppend("float texColor = ");
-        fragBuilder->appendTextureLookup(args.fTexSamplers[0], "uv", kVec2f_GrSLType);
-        fragBuilder->codeAppend(".r;");
         fragBuilder->codeAppend("float distance = "
-            SK_DistanceFieldMultiplier "*(texColor - " SK_DistanceFieldThreshold ");");
+            SK_DistanceFieldMultiplier "*(texColor.r - " SK_DistanceFieldThreshold ");");
 
         fragBuilder->codeAppend("float afwidth;");
         bool isUniformScale = (dfTexEffect.getFlags() & kUniformScale_DistanceFieldEffectMask) ==
@@ -452,7 +440,7 @@ public:
             pdman.setMatrix3f(fViewMatrixUniform, viewMatrix);
         }
 
-        SkASSERT(dfpgp.numTextureSamplers() == 1);
+        SkASSERT(dfpgp.numTextureSamplers() >= 1);
         GrTexture* atlas = dfpgp.textureSampler(0).peekTexture();
         SkASSERT(atlas && SkIsPow2(atlas->width()) && SkIsPow2(atlas->height()));
 
@@ -472,6 +460,7 @@ public:
         uint32_t key = dfTexEffect.getFlags();
         key |= ComputePosKey(dfTexEffect.viewMatrix()) << 16;
         b->add32(key);
+        b->add32(dfTexEffect.numTextureSamplers());
     }
 
 private:
@@ -599,17 +588,10 @@ public:
 
         // set up varyings
         GrGLSLVertToFrag uv(kVec2f_GrSLType);
-        varyingHandler->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y) * %s;", uv.vsOut(),
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 atlasSizeInvName);
-
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
         GrGLSLVertToFrag st(kVec2f_GrSLType);
-        varyingHandler->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y);", st.vsOut(),
-                                 dfTexEffect.inTextureCoords()->fName,
-                                 dfTexEffect.inTextureCoords()->fName);
+        append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &texIdx, &st);
 
         GrGLSLVertToFrag delta(kFloat_GrSLType);
         varyingHandler->addVarying("Delta", &delta, kHigh_GrSLPrecision);
@@ -660,26 +642,26 @@ public:
             fragBuilder->codeAppendf("float2 offset = %s*Jdx;", delta.fsIn());
         }
 
+        // sample the texture by index
+        fragBuilder->codeAppend("float4 texColor;");
+        append_multitexture_lookup(args, dfTexEffect.numTextureSamplers(),
+                                   texIdx, "uv", "texColor");
+
         // green is distance to uv center
-        fragBuilder->codeAppend("\tfloat4 texColor = ");
-        fragBuilder->appendTextureLookup(args.fTexSamplers[0], "uv", kVec2f_GrSLType);
-        fragBuilder->codeAppend(";\n");
-        fragBuilder->codeAppend("\tfloat3 distance;\n");
-        fragBuilder->codeAppend("\tdistance.y = texColor.r;\n");
+        fragBuilder->codeAppend("float3 distance;");
+        fragBuilder->codeAppend("distance.y = texColor.r;");
         // red is distance to left offset
-        fragBuilder->codeAppend("\tfloat2 uv_adjusted = uv - offset;\n");
-        fragBuilder->codeAppend("\ttexColor = ");
-        fragBuilder->appendTextureLookup(args.fTexSamplers[0], "uv_adjusted", kVec2f_GrSLType);
-        fragBuilder->codeAppend(";\n");
-        fragBuilder->codeAppend("\tdistance.x = texColor.r;\n");
+        fragBuilder->codeAppend("float2 uv_adjusted = uv - offset;");
+        append_multitexture_lookup(args, dfTexEffect.numTextureSamplers(),
+                                   texIdx, "uv_adjusted", "texColor");
+        fragBuilder->codeAppend("distance.x = texColor.r;");
         // blue is distance to right offset
-        fragBuilder->codeAppend("\tuv_adjusted = uv + offset;\n");
-        fragBuilder->codeAppend("\ttexColor = ");
-        fragBuilder->appendTextureLookup(args.fTexSamplers[0], "uv_adjusted", kVec2f_GrSLType);
-        fragBuilder->codeAppend(";\n");
-        fragBuilder->codeAppend("\tdistance.z = texColor.r;\n");
+        fragBuilder->codeAppend("uv_adjusted = uv + offset;");
+        append_multitexture_lookup(args, dfTexEffect.numTextureSamplers(),
+                                   texIdx, "uv_adjusted", "texColor");
+        fragBuilder->codeAppend("distance.z = texColor.r;");
 
-        fragBuilder->codeAppend("\tdistance = "
+        fragBuilder->codeAppend("distance = "
            "float3(" SK_DistanceFieldMultiplier ")*(distance - float3(" SK_DistanceFieldThreshold"));");
 
         // adjust width based on gamma
@@ -757,7 +739,7 @@ public:
             pdman.setMatrix3f(fViewMatrixUniform, viewMatrix);
         }
 
-        SkASSERT(dflcd.numTextureSamplers() == 1);
+        SkASSERT(dflcd.numTextureSamplers() >= 1);
         GrTexture* atlas = dflcd.textureSampler(0).peekTexture();
         SkASSERT(atlas && SkIsPow2(atlas->width()) && SkIsPow2(atlas->height()));
 
@@ -777,6 +759,7 @@ public:
         uint32_t key = dfTexEffect.getFlags();
         key |= ComputePosKey(dfTexEffect.viewMatrix()) << 16;
         b->add32(key);
+        b->add32(dfTexEffect.numTextureSamplers());
     }
 
 private: