Add multitexture support to text and path shaders

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: I636b329a6f748b6753f5f92a70066fb412623df2
Reviewed-on: https://skia-review.googlesource.com/43000
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

3 files changed, 115 insertions, 73 deletions

diff --git a/src/gpu/effects/GrAtlasedShaderHelpers.h b/src/gpu/effects/GrAtlasedShaderHelpers.h
new file mode 100644
index 0000000000..c7d1a41c10
--- /dev/null
+++ b/src/gpu/effects/GrAtlasedShaderHelpers.h
@@ -0,0 +1,60 @@
+/*
+ * 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 *st,
+                                     GrGLSLVertToFrag *texIdx) {
+    // 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 intCoords = floor(0.5*float2(%s.x, %s.y));",
+                                   inTexCoordsName, inTexCoordsName);
+    args.fVertBuilder->codeAppendf("float2 diff = %s - 2.0*intCoords;", inTexCoordsName);
+    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("IntTextureCoords", st, kHigh_GrSLPrecision);
+    args.fVertBuilder->codeAppendf("%s = intCoords;", st->vsOut());
+
+    args.fVaryingHandler->addVarying("TexIndex", texIdx);
+    args.fVertBuilder->codeAppendf("%s = texIdx;", texIdx->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..fab0904a4f 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 +37,11 @@ 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 st(kVec2f_GrSLType);
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
+        append_index_uv_varyings(args, btgp.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &st, &texIdx);
 
         GrGLSLPPFragmentBuilder* fragBuilder = args.fFragBuilder;
         // Setup pass through color
@@ -64,18 +64,16 @@ 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 +87,7 @@ 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 +106,7 @@ 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..b8f0386820 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 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);
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
+        append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &st, &texIdx);
 
         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 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);
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
+        append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &st, &texIdx);
 
         // 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 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);
+        GrGLSLVertToFrag texIdx(kFloat_GrSLType);
+        append_index_uv_varyings(args, dfTexEffect.inTextureCoords()->fName, atlasSizeInvName,
+                                 &uv, &st, &texIdx);
 
         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: