/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "WebGLVertexAttribData.h"

#include "GLContext.h"
#include "WebGLBuffer.h"

namespace mozilla {

static uint8_t CalcBytesPerVertex(GLenum type, uint8_t size) {
  uint8_t bytesPerType;
  switch (type) {
    case LOCAL_GL_INT_2_10_10_10_REV:
    case LOCAL_GL_UNSIGNED_INT_2_10_10_10_REV:
      return 4;

    case LOCAL_GL_BYTE:
    case LOCAL_GL_UNSIGNED_BYTE:
      bytesPerType = 1;
      break;

    case LOCAL_GL_HALF_FLOAT:
    case LOCAL_GL_SHORT:
    case LOCAL_GL_UNSIGNED_SHORT:
      bytesPerType = 2;
      break;

    case LOCAL_GL_FIXED:  // GLES 3.0.4 p9: 32-bit signed, with 16 fractional
                          // bits.
    case LOCAL_GL_FLOAT:
    case LOCAL_GL_INT:
    case LOCAL_GL_UNSIGNED_INT:
      bytesPerType = 4;
      break;

    default:
      MOZ_CRASH("Bad `type`.");
  }

  return bytesPerType * size;
}

static GLenum AttribPointerBaseType(bool integerFunc, GLenum type) {
  if (!integerFunc) return LOCAL_GL_FLOAT;

  switch (type) {
    case LOCAL_GL_BYTE:
    case LOCAL_GL_SHORT:
    case LOCAL_GL_INT:
      return LOCAL_GL_INT;

    case LOCAL_GL_UNSIGNED_BYTE:
    case LOCAL_GL_UNSIGNED_SHORT:
    case LOCAL_GL_UNSIGNED_INT:
      return LOCAL_GL_UNSIGNED_INT;

    default:
      MOZ_CRASH();
  }
}

void WebGLVertexAttribData::VertexAttribPointer(bool integerFunc,
                                                WebGLBuffer* buf, uint8_t size,
                                                GLenum type, bool normalized,
                                                uint32_t stride,
                                                uint64_t byteOffset) {
  mIntegerFunc = integerFunc;
  WebGLBuffer::SetSlot(0, buf, &mBuf);
  mType = type;
  mBaseType = AttribPointerBaseType(integerFunc, type);
  mSize = size;
  mBytesPerVertex = CalcBytesPerVertex(mType, mSize);
  mNormalized = normalized;
  mStride = stride;
  mExplicitStride = (mStride ? mStride : mBytesPerVertex);
  mByteOffset = byteOffset;
}

void WebGLVertexAttribData::DoVertexAttribPointer(gl::GLContext* gl,
                                                  GLuint index) const {
  if (mIntegerFunc) {
    gl->fVertexAttribIPointer(index, mSize, mType, mStride,
                              (const void*)mByteOffset);
  } else {
    gl->fVertexAttribPointer(index, mSize, mType, mNormalized, mStride,
                             (const void*)mByteOffset);
  }
}

}  // namespace mozilla