Revert "Hard code bicubic coefficients in the shader"

This reverts commit 81ad5f744a775826c0d68bf035e891ae178f89d2.

Reason for revert: Serious regressions on Tegra3, and significant regression on Adreno 530.

Original change's description:
> Hard code bicubic coefficients in the shader
> 
> BUG=skia:
> 
> Change-Id: Ie231a9bd2ea2083005a595e9e426590da740b2ed
> Reviewed-on: https://skia-review.googlesource.com/6619
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>
> 

TBR=bsalomon@google.com,robertphillips@google.com,brianosman@google.com,reviews@skia.org
BUG=skia:
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I62b26f2a67e8a245c36bb6098c5cb9fbed21bb8f
Reviewed-on: https://skia-review.googlesource.com/6630
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

1 files changed, 60 insertions, 35 deletions

diff --git a/src/gpu/effects/GrBicubicEffect.cpp b/src/gpu/effects/GrBicubicEffect.cpp
index 9d8e728efc..de93aaacc6 100644
--- a/src/gpu/effects/GrBicubicEffect.cpp
+++ b/src/gpu/effects/GrBicubicEffect.cpp
@@ -13,6 +13,32 @@
 #include "glsl/GrGLSLUniformHandler.h"
 #include "../private/GrGLSL.h"
 
+/*
+ * Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer
+ * Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988).
+ * ACM DL: http://dl.acm.org/citation.cfm?id=378514
+ * Free  : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf
+ *
+ * The authors define a family of cubic filters with two free parameters (B and C):
+ *
+ *            { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B)            if |x| < 1
+ * k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C)   if 1 <= |x| < 2
+ *            { 0                                                                 otherwise
+ *
+ * Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their
+ * favorite overall spline - this is now commonly known as the Mitchell filter, and is the source
+ * of the specific weights below.
+ *
+ * These weights are in column-major order (ie this matrix is transposed from what you'd expect),
+ * so we can upload them directly via setMatrix4f.
+ */
+static constexpr float kMitchellCoefficients[16] = {
+     1.0f / 18.0f,  16.0f / 18.0f,   1.0f / 18.0f,  0.0f / 18.0f,
+    -9.0f / 18.0f,   0.0f / 18.0f,   9.0f / 18.0f,  0.0f / 18.0f,
+    15.0f / 18.0f, -36.0f / 18.0f,  27.0f / 18.0f, -6.0f / 18.0f,
+    -7.0f / 18.0f,  21.0f / 18.0f, -21.0f / 18.0f,  7.0f / 18.0f,
+};
+
 class GrGLBicubicEffect : public GrGLSLFragmentProcessor {
 public:
     void emitCode(EmitArgs&) override;
@@ -30,6 +56,7 @@ protected:
 private:
     typedef GrGLSLProgramDataManager::UniformHandle UniformHandle;
 
+    UniformHandle               fCoefficientsUni;
     UniformHandle               fImageIncrementUni;
     UniformHandle               fColorSpaceXformUni;
     GrTextureDomain::GLDomain   fDomain;
@@ -41,52 +68,48 @@ void GrGLBicubicEffect::emitCode(EmitArgs& args) {
     const GrBicubicEffect& bicubicEffect = args.fFp.cast<GrBicubicEffect>();
 
     GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
+    fCoefficientsUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
+                                                  kMat44f_GrSLType, kDefault_GrSLPrecision,
+                                                  "Coefficients");
     fImageIncrementUni = uniformHandler->addUniform(kFragment_GrShaderFlag,
                                                     kVec2f_GrSLType, kDefault_GrSLPrecision,
                                                     "ImageIncrement");
 
     const char* imgInc = uniformHandler->getUniformCStr(fImageIncrementUni);
+    const char* coeff = uniformHandler->getUniformCStr(fCoefficientsUni);
 
     GrGLSLColorSpaceXformHelper colorSpaceHelper(uniformHandler, bicubicEffect.colorSpaceXform(),
                                                  &fColorSpaceXformUni);
 
+    SkString cubicBlendName;
+
+    static const GrShaderVar gCubicBlendArgs[] = {
+        GrShaderVar("coefficients",  kMat44f_GrSLType),
+        GrShaderVar("t",             kFloat_GrSLType),
+        GrShaderVar("c0",            kVec4f_GrSLType),
+        GrShaderVar("c1",            kVec4f_GrSLType),
+        GrShaderVar("c2",            kVec4f_GrSLType),
+        GrShaderVar("c3",            kVec4f_GrSLType),
+    };
     GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
     SkString coords2D = fragBuilder->ensureCoords2D(args.fTransformedCoords[0]);
-
-    /*
-     * Filter weights come from Don Mitchell & Arun Netravali's 'Reconstruction Filters in Computer
-     * Graphics', ACM SIGGRAPH Computer Graphics 22, 4 (Aug. 1988).
-     * ACM DL: http://dl.acm.org/citation.cfm?id=378514
-     * Free  : http://www.cs.utexas.edu/users/fussell/courses/cs384g/lectures/mitchell/Mitchell.pdf
-     *
-     * The authors define a family of cubic filters with two free parameters (B and C):
-     *
-     *            { (12 - 9B - 6C)|x|^3 + (-18 + 12B + 6C)|x|^2 + (6 - 2B)          if |x| < 1
-     * k(x) = 1/6 { (-B - 6C)|x|^3 + (6B + 30C)|x|^2 + (-12B - 48C)|x| + (8B + 24C) if 1 <= |x| < 2
-     *            { 0                                                               otherwise
-     *
-     * Various well-known cubic splines can be generated, and the authors select (1/3, 1/3) as their
-     * favorite overall spline - this is now commonly known as the Mitchell filter, and is the
-     * source of the specific weights below.
-     *
-     * This is GLSL, so the matrix is column-major (transposed from standard matrix notation).
-     */
-    fragBuilder->codeAppend("mat4 kMitchellCoefficients = mat4("
-                            " 1.0 / 18.0,  16.0 / 18.0,   1.0 / 18.0,  0.0 / 18.0,"
-                            "-9.0 / 18.0,   0.0 / 18.0,   9.0 / 18.0,  0.0 / 18.0,"
-                            "15.0 / 18.0, -36.0 / 18.0,  27.0 / 18.0, -6.0 / 18.0,"
-                            "-7.0 / 18.0,  21.0 / 18.0, -21.0 / 18.0,  7.0 / 18.0);");
-    fragBuilder->codeAppendf("vec2 coord = %s - %s * vec2(0.5);", coords2D.c_str(), imgInc);
+    fragBuilder->emitFunction(kVec4f_GrSLType,
+                              "cubicBlend",
+                              SK_ARRAY_COUNT(gCubicBlendArgs),
+                              gCubicBlendArgs,
+                              "\tvec4 ts = vec4(1.0, t, t * t, t * t * t);\n"
+                              "\tvec4 c = coefficients * ts;\n"
+                              "\treturn c.x * c0 + c.y * c1 + c.z * c2 + c.w * c3;\n",
+                              &cubicBlendName);
+    fragBuilder->codeAppendf("\tvec2 coord = %s - %s * vec2(0.5);\n", coords2D.c_str(), imgInc);
     // We unnormalize the coord in order to determine our fractional offset (f) within the texel
     // We then snap coord to a texel center and renormalize. The snap prevents cases where the
     // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
     // double hit a texel.
-    fragBuilder->codeAppendf("coord /= %s;", imgInc);
-    fragBuilder->codeAppend("vec2 f = fract(coord);");
-    fragBuilder->codeAppendf("coord = (coord - f + vec2(0.5)) * %s;", imgInc);
-    fragBuilder->codeAppend("vec4 wx = kMitchellCoefficients * vec4(1.0, f.x, f.x * f.x, f.x * f.x * f.x);");
-    fragBuilder->codeAppend("vec4 wy = kMitchellCoefficients * vec4(1.0, f.y, f.y * f.y, f.y * f.y * f.y);");
-    fragBuilder->codeAppend("vec4 rowColors[4];");
+    fragBuilder->codeAppendf("\tcoord /= %s;\n", imgInc);
+    fragBuilder->codeAppend("\tvec2 f = fract(coord);\n");
+    fragBuilder->codeAppendf("\tcoord = (coord - f + vec2(0.5)) * %s;\n", imgInc);
+    fragBuilder->codeAppend("\tvec4 rowColors[4];\n");
     for (int y = 0; y < 4; ++y) {
         for (int x = 0; x < 4; ++x) {
             SkString coord;
@@ -102,16 +125,17 @@ void GrGLBicubicEffect::emitCode(EmitArgs& args) {
                                   args.fTexSamplers[0]);
         }
         fragBuilder->codeAppendf(
-            "vec4 s%d = wx.x * rowColors[0] + wx.y * rowColors[1] + wx.z * rowColors[2] + wx.w * rowColors[3];",
-            y);
+            "\tvec4 s%d = %s(%s, f.x, rowColors[0], rowColors[1], rowColors[2], rowColors[3]);\n",
+            y, cubicBlendName.c_str(), coeff);
     }
-    SkString bicubicColor("(wy.x * s0 + wy.y * s1 + wy.z * s2 + wy.w * s3)");
+    SkString bicubicColor;
+    bicubicColor.printf("%s(%s, f.y, s0, s1, s2, s3)", cubicBlendName.c_str(), coeff);
     if (colorSpaceHelper.getXformMatrix()) {
         SkString xformedColor;
         fragBuilder->appendColorGamutXform(&xformedColor, bicubicColor.c_str(), &colorSpaceHelper);
         bicubicColor.swap(xformedColor);
     }
-    fragBuilder->codeAppendf("%s = %s;",
+    fragBuilder->codeAppendf("\t%s = %s;\n",
                              args.fOutputColor, (GrGLSLExpr4(bicubicColor.c_str()) *
                                                  GrGLSLExpr4(args.fInputColor)).c_str());
 }
@@ -124,6 +148,7 @@ void GrGLBicubicEffect::onSetData(const GrGLSLProgramDataManager& pdman,
     imageIncrement[0] = 1.0f / texture->width();
     imageIncrement[1] = 1.0f / texture->height();
     pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
+    pdman.setMatrix4f(fCoefficientsUni, kMitchellCoefficients);
     fDomain.setData(pdman, bicubicEffect.domain(), texture->origin());
     if (SkToBool(bicubicEffect.colorSpaceXform())) {
         pdman.setSkMatrix44(fColorSpaceXformUni, bicubicEffect.colorSpaceXform()->srcToDst());