Correctly handle mat2x2 in Vulkan

src/gpu/vk/GrVkUniformHandler.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "GrVkUniformHandler.h"
 #include "glsl/GrGLSLProgramBuilder.h"
 
@@ skipping 35 matching lines @@
     GR_STATIC_ASSERT(10 == kSampler2DRect_GrSLType);
     GR_STATIC_ASSERT(11 == kSamplerBuffer_GrSLType);
     GR_STATIC_ASSERT(12 == kBool_GrSLType);
     GR_STATIC_ASSERT(13 == kInt_GrSLType);
     GR_STATIC_ASSERT(14 == kUint_GrSLType);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kAlignmentMask) == kGrSLTypeCount);
     return kAlignmentMask[type];
 }
 
 /** Returns the size in bytes taken up in vulkanbuffers for floating point GrSLTypes.
-    For non floating point type returns 0 */
+    For non floating point type returns 0. Currently this reflects the std140 alignment
+    so a mat22 takes up 8 floats. */
 static inline uint32_t grsltype_to_vk_size(GrSLType type) {
     SkASSERT(GrSLTypeIsFloatType(type));
-    SkASSERT(kMat22f_GrSLType != type); // TODO: handle mat2 differences between std140 and std430.
     static const uint32_t kSizes[] = {
         0,                        // kVoid_GrSLType
         sizeof(float),            // kFloat_GrSLType
         2 * sizeof(float),        // kVec2f_GrSLType
         3 * sizeof(float),        // kVec3f_GrSLType
         4 * sizeof(float),        // kVec4f_GrSLType
         8 * sizeof(float),        // kMat22f_GrSLType. TODO: this will be 4 * szof(float) on std430.
         12 * sizeof(float),       // kMat33f_GrSLType
         16 * sizeof(float),       // kMat44f_GrSLType
         0,                        // kSampler2D_GrSLType
@@ skipping 27 matching lines @@
 
 // Given the current offset into the ubo, calculate the offset for the uniform we're trying to add
 // taking into consideration all alignment requirements. The uniformOffset is set to the offset for
 // the new uniform, and currentOffset is updated to be the offset to the end of the new uniform.
 void get_ubo_aligned_offset(uint32_t* uniformOffset,
                             uint32_t* currentOffset,
                             GrSLType type,
                             int arrayCount) {
     uint32_t alignmentMask = grsltype_to_alignment_mask(type);
     // We want to use the std140 layout here, so we must make arrays align to 16 bytes.
-    SkASSERT(type != kMat22f_GrSLType); // TODO: support mat2.
-    if (arrayCount) {
+    if (arrayCount || type == kMat22f_GrSLType) {
         alignmentMask = 0xF;
     }
     uint32_t offsetDiff = *currentOffset & alignmentMask;
     if (offsetDiff != 0) {
         offsetDiff = alignmentMask - offsetDiff + 1;
     }
     *uniformOffset = *currentOffset + offsetDiff;
     SkASSERT(sizeof(float) == 4);
     if (arrayCount) {
         uint32_t elementSize = SkTMax<uint32_t>(16, grsltype_to_vk_size(type));
@@ skipping 93 matching lines @@
     }
     if (!uniformsString.isEmpty()) {
         uint32_t uniformBinding = (visibility == kVertex_GrShaderFlag) ? kVertexBinding
                                                                        : kFragBinding;
         const char* stage = (visibility == kVertex_GrShaderFlag) ? "vertex" : "fragment";
         out->appendf("layout (set=%d, binding=%d) uniform %sUniformBuffer\n{\n",
                      kUniformBufferDescSet, uniformBinding, stage);
         out->appendf("%s\n};\n", uniformsString.c_str());
     }
 }