src/libGLESv2/validationES2.cpp

#include "precompiled.h"
//
// Copyright (c) 2013 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

// validationES2.cpp: Validation functions for OpenGL ES 2.0 entry point parameters

#include "libGLESv2/validationES2.h"
#include "libGLESv2/validationES.h"
#include "libGLESv2/Context.h"
#include "libGLESv2/Texture.h"
#include "libGLESv2/Framebuffer.h"
#include "libGLESv2/Renderbuffer.h"
#include "libGLESv2/formatutils.h"
#include "libGLESv2/main.h"

#include "common/mathutil.h"
#include "common/utilities.h"

namespace gl
{

static bool validCompressedImageSize(GLsizei width, GLsizei height)
{
    if (width != 1 && width != 2 && width % 4 != 0)
    {
        return false;
    }

    if (height != 1 && height != 2 && height % 4 != 0)
    {
        return false;
    }

    return true;
}

static bool validateSubImageParams2D(bool compressed, GLsizei width, GLsizei height,
                                     GLint xoffset, GLint yoffset, GLint level, GLenum format, GLenum type,
                                     gl::Texture2D *texture)
{
    if (!texture)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (compressed != texture->isCompressed(level))
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (format != GL_NONE)
    {
        GLenum internalformat = gl::GetSizedInternalFormat(format, type, 2);
        if (internalformat != texture->getInternalFormat(level))
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }
    }

    if (compressed)
    {
        if ((width % 4 != 0 && width != texture->getWidth(0)) ||
            (height % 4 != 0 && height != texture->getHeight(0)))
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }
    }

    if (xoffset + width > texture->getWidth(level) ||
        yoffset + height > texture->getHeight(level))
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    return true;
}

static bool validateSubImageParamsCube(bool compressed, GLsizei width, GLsizei height,
                                       GLint xoffset, GLint yoffset, GLenum target, GLint level, GLenum format, GLenum type,
                                       gl::TextureCubeMap *texture)
{
    if (!texture)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (compressed != texture->isCompressed(target, level))
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (format != GL_NONE)
    {
        GLenum internalformat = gl::GetSizedInternalFormat(format, type, 2);
        if (internalformat != texture->getInternalFormat(target, level))
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }
    }

    if (compressed)
    {
        if ((width % 4 != 0 && width != texture->getWidth(target, 0)) ||
            (height % 4 != 0 && height != texture->getHeight(target, 0)))
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }
    }

    if (xoffset + width > texture->getWidth(target, level) ||
        yoffset + height > texture->getHeight(target, level))
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    return true;
}

bool ValidateES2TexImageParameters(gl::Context *context, GLenum target, GLint level, GLint internalformat, bool isCompressed, bool isSubImage,
                                   GLint xoffset, GLint yoffset, GLsizei width, GLsizei height,
                                   GLint border, GLenum format, GLenum type, const GLvoid *pixels)
{
    if (!ValidImageSize(context, target, level, width, height, 1))
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    if (isCompressed && !validCompressedImageSize(width, height))
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (level < 0 || xoffset < 0 ||
        std::numeric_limits<GLsizei>::max() - xoffset < width ||
        std::numeric_limits<GLsizei>::max() - yoffset < height)
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    if (!isSubImage && !isCompressed && internalformat != GLint(format))
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    gl::Texture *texture = NULL;
    bool textureCompressed = false;
    GLenum textureInternalFormat = GL_NONE;
    GLint textureLevelWidth = 0;
    GLint textureLevelHeight = 0;
    switch (target)
    {
      case GL_TEXTURE_2D:
        {
            if (width > (context->getMaximum2DTextureDimension() >> level) ||
                height > (context->getMaximum2DTextureDimension() >> level))
            {
                return gl::error(GL_INVALID_VALUE, false);
            }

            gl::Texture2D *tex2d = context->getTexture2D();
            if (tex2d)
            {
                textureCompressed = tex2d->isCompressed(level);
                textureInternalFormat = tex2d->getInternalFormat(level);
                textureLevelWidth = tex2d->getWidth(level);
                textureLevelHeight = tex2d->getHeight(level);
                texture = tex2d;
            }

            if (isSubImage && !validateSubImageParams2D(isCompressed, width, height, xoffset, yoffset,
                                                        level, format, type, tex2d))
            {
                return false;
            }

            texture = tex2d;
        }
        break;

      case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
      case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
      case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
      case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
      case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
      case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
        {
            if (!isSubImage && width != height)
            {
                return gl::error(GL_INVALID_VALUE, false);
            }

            if (width > (context->getMaximumCubeTextureDimension() >> level) ||
                height > (context->getMaximumCubeTextureDimension() >> level))
            {
                return gl::error(GL_INVALID_VALUE, false);
            }

            gl::TextureCubeMap *texCube = context->getTextureCubeMap();
            if (texCube)
            {
                textureCompressed = texCube->isCompressed(target, level);
                textureInternalFormat = texCube->getInternalFormat(target, level);
                textureLevelWidth = texCube->getWidth(target, level);
                textureLevelHeight = texCube->getHeight(target, level);
                texture = texCube;
            }

            if (isSubImage && !validateSubImageParamsCube(isCompressed, width, height, xoffset, yoffset,
                                                          target, level, format, type, texCube))
            {
                return false;
            }
        }
        break;

      default:
        return gl::error(GL_INVALID_ENUM, false);
    }

    if (!texture)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (!isSubImage && texture->isImmutable())
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    // Verify zero border
    if (border != 0)
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    GLenum actualInternalFormat = isSubImage ? textureInternalFormat : internalformat;
    if (isCompressed)
    {
        switch (actualInternalFormat)
        {
          case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
          case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
            if (!context->supportsDXT1Textures())
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_COMPRESSED_RGBA_S3TC_DXT3_ANGLE:
            if (!context->supportsDXT3Textures())
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE:
            if (!context->supportsDXT5Textures())
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          default:
            return gl::error(GL_INVALID_ENUM, false);
        }
    }
    else
    {
        // validate <type> by itself (used as secondary key below)
        switch (type)
        {
          case GL_UNSIGNED_BYTE:
          case GL_UNSIGNED_SHORT_5_6_5:
          case GL_UNSIGNED_SHORT_4_4_4_4:
          case GL_UNSIGNED_SHORT_5_5_5_1:
          case GL_UNSIGNED_SHORT:
          case GL_UNSIGNED_INT:
          case GL_UNSIGNED_INT_24_8_OES:
          case GL_HALF_FLOAT_OES:
          case GL_FLOAT:
            break;
          default:
            return gl::error(GL_INVALID_ENUM, false);
        }

        // validate <format> + <type> combinations
        // - invalid <format> -> sets INVALID_ENUM
        // - invalid <format>+<type> combination -> sets INVALID_OPERATION
        switch (format)
        {
          case GL_ALPHA:
          case GL_LUMINANCE:
          case GL_LUMINANCE_ALPHA:
            switch (type)
            {
              case GL_UNSIGNED_BYTE:
              case GL_FLOAT:
              case GL_HALF_FLOAT_OES:
                break;
            default:
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_RGB:
            switch (type)
            {
              case GL_UNSIGNED_BYTE:
              case GL_UNSIGNED_SHORT_5_6_5:
              case GL_FLOAT:
              case GL_HALF_FLOAT_OES:
                break;
              default:
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_RGBA:
            switch (type)
            {
              case GL_UNSIGNED_BYTE:
              case GL_UNSIGNED_SHORT_4_4_4_4:
              case GL_UNSIGNED_SHORT_5_5_5_1:
              case GL_FLOAT:
              case GL_HALF_FLOAT_OES:
                break;
              default:
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_BGRA_EXT:
            switch (type)
            {
              case GL_UNSIGNED_BYTE:
                break;
              default:
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:  // error cases for compressed textures are handled below
          case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
          case GL_COMPRESSED_RGBA_S3TC_DXT3_ANGLE:
          case GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE:
            break;
          case GL_DEPTH_COMPONENT:
            switch (type)
            {
              case GL_UNSIGNED_SHORT:
              case GL_UNSIGNED_INT:
                break;
              default:
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_DEPTH_STENCIL_OES:
            switch (type)
            {
              case GL_UNSIGNED_INT_24_8_OES:
                break;
              default:
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          default:
            return gl::error(GL_INVALID_ENUM, false);
        }

        switch (format)
        {
          case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
          case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
            if (context->supportsDXT1Textures())
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            else
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_COMPRESSED_RGBA_S3TC_DXT3_ANGLE:
            if (context->supportsDXT3Textures())
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            else
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE:
            if (context->supportsDXT5Textures())
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            else
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_DEPTH_COMPONENT:
          case GL_DEPTH_STENCIL_OES:
            if (!context->supportsDepthTextures())
            {
                return gl::error(GL_INVALID_VALUE, false);
            }
            if (target != GL_TEXTURE_2D)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            // OES_depth_texture supports loading depth data and multiple levels,
            // but ANGLE_depth_texture does not
            if (pixels != NULL || level != 0)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          default:
            break;
        }

        if (type == GL_FLOAT)
        {
            if (!context->supportsFloat32Textures())
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
        }
        else if (type == GL_HALF_FLOAT_OES)
        {
            if (!context->supportsFloat16Textures())
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
        }
    }

    return true;
}



bool ValidateES2CopyTexImageParameters(gl::Context* context, GLenum target, GLint level, GLenum internalformat, bool isSubImage,
                                       GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width, GLsizei height,
                                       GLint border)
{
    if (!gl::IsInternalTextureTarget(target, context->getClientVersion()))
    {
        return gl::error(GL_INVALID_ENUM, false);
    }

    if (level < 0 || xoffset < 0 || yoffset < 0 || width < 0 || height < 0)
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    if (std::numeric_limits<GLsizei>::max() - xoffset < width || std::numeric_limits<GLsizei>::max() - yoffset < height)
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    // Verify zero border
    if (border != 0)
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    // Validate dimensions based on Context limits and validate the texture
    if (!ValidMipLevel(context, target, level))
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    gl::Framebuffer *framebuffer = context->getReadFramebuffer();

    if (framebuffer->completeness() != GL_FRAMEBUFFER_COMPLETE)
    {
        return gl::error(GL_INVALID_FRAMEBUFFER_OPERATION, false);
    }

    if (context->getReadFramebufferHandle() != 0 && framebuffer->getSamples() != 0)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    GLenum colorbufferFormat = framebuffer->getReadColorbuffer()->getInternalFormat();
    gl::Texture *texture = NULL;
    GLenum textureFormat = GL_RGBA;

    switch (target)
    {
      case GL_TEXTURE_2D:
        {
            if (width > (context->getMaximum2DTextureDimension() >> level) ||
                height > (context->getMaximum2DTextureDimension() >> level))
            {
                return gl::error(GL_INVALID_VALUE, false);
            }

            gl::Texture2D *tex2d = context->getTexture2D();
            if (tex2d)
            {
                if (isSubImage && !validateSubImageParams2D(false, width, height, xoffset, yoffset, level, GL_NONE, GL_NONE, tex2d))
                {
                    return false; // error already registered by validateSubImageParams
                }
                texture = tex2d;
                textureFormat = gl::GetFormat(tex2d->getInternalFormat(level), context->getClientVersion());
            }
        }
        break;

      case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
      case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
      case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
      case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
      case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
      case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
        {
            if (!isSubImage && width != height)
            {
                return gl::error(GL_INVALID_VALUE, false);
            }

            if (width > (context->getMaximumCubeTextureDimension() >> level) ||
                height > (context->getMaximumCubeTextureDimension() >> level))
            {
                return gl::error(GL_INVALID_VALUE, false);
            }

            gl::TextureCubeMap *texcube = context->getTextureCubeMap();
            if (texcube)
            {
                if (isSubImage && !validateSubImageParamsCube(false, width, height, xoffset, yoffset, target, level, GL_NONE, GL_NONE, texcube))
                {
                    return false; // error already registered by validateSubImageParams
                }
                texture = texcube;
                textureFormat = gl::GetFormat(texcube->getInternalFormat(target, level), context->getClientVersion());
            }
        }
        break;

      default:
        return gl::error(GL_INVALID_ENUM, false);
    }

    if (!texture)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (texture->isImmutable() && !isSubImage)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }


    // [OpenGL ES 2.0.24] table 3.9
    if (isSubImage)
    {
        switch (textureFormat)
        {
          case GL_ALPHA:
            if (colorbufferFormat != GL_ALPHA8_EXT &&
                colorbufferFormat != GL_RGBA4 &&
                colorbufferFormat != GL_RGB5_A1 &&
                colorbufferFormat != GL_RGBA8_OES)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_LUMINANCE:
          case GL_RGB:
            if (colorbufferFormat != GL_RGB565 &&
                colorbufferFormat != GL_RGB8_OES &&
                colorbufferFormat != GL_RGBA4 &&
                colorbufferFormat != GL_RGB5_A1 &&
                colorbufferFormat != GL_RGBA8_OES)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_LUMINANCE_ALPHA:
          case GL_RGBA:
            if (colorbufferFormat != GL_RGBA4 &&
                colorbufferFormat != GL_RGB5_A1 &&
                colorbufferFormat != GL_RGBA8_OES)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
          case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
          case GL_COMPRESSED_RGBA_S3TC_DXT3_ANGLE:
          case GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE:
            return gl::error(GL_INVALID_OPERATION, false);
          case GL_DEPTH_COMPONENT:
          case GL_DEPTH_STENCIL_OES:
            return gl::error(GL_INVALID_OPERATION, false);
          default:
            return gl::error(GL_INVALID_OPERATION, false);
        }
    }
    else
    {
        switch (internalformat)
        {
          case GL_ALPHA:
            if (colorbufferFormat != GL_ALPHA8_EXT &&
                colorbufferFormat != GL_RGBA4 &&
                colorbufferFormat != GL_RGB5_A1 &&
                colorbufferFormat != GL_BGRA8_EXT &&
                colorbufferFormat != GL_RGBA8_OES)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_LUMINANCE:
          case GL_RGB:
            if (colorbufferFormat != GL_RGB565 &&
                colorbufferFormat != GL_RGB8_OES &&
                colorbufferFormat != GL_RGBA4 &&
                colorbufferFormat != GL_RGB5_A1 &&
                colorbufferFormat != GL_BGRA8_EXT &&
                colorbufferFormat != GL_RGBA8_OES)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_LUMINANCE_ALPHA:
          case GL_RGBA:
            if (colorbufferFormat != GL_RGBA4 &&
                colorbufferFormat != GL_RGB5_A1 &&
                colorbufferFormat != GL_BGRA8_EXT &&
                colorbufferFormat != GL_RGBA8_OES)
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            break;
          case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
          case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
            if (context->supportsDXT1Textures())
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            else
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_COMPRESSED_RGBA_S3TC_DXT3_ANGLE:
            if (context->supportsDXT3Textures())
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            else
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE:
            if (context->supportsDXT5Textures())
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            else
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
            break;
          case GL_DEPTH_COMPONENT:
          case GL_DEPTH_COMPONENT16:
          case GL_DEPTH_COMPONENT32_OES:
          case GL_DEPTH_STENCIL_OES:
          case GL_DEPTH24_STENCIL8_OES:
            if (context->supportsDepthTextures())
            {
                return gl::error(GL_INVALID_OPERATION, false);
            }
            else
            {
                return gl::error(GL_INVALID_ENUM, false);
            }
          default:
            return gl::error(GL_INVALID_ENUM, false);
        }
    }

    // If width or height is zero, it is a no-op.  Return false without setting an error.
    return (width > 0 && height > 0);
}

bool ValidateES2TexStorageParameters(gl::Context *context, GLenum target, GLsizei levels, GLenum internalformat,
                                     GLsizei width, GLsizei height)
{
    if (target != GL_TEXTURE_2D && target != GL_TEXTURE_CUBE_MAP)
    {
        return gl::error(GL_INVALID_ENUM, false);
    }

    if (width < 1 || height < 1 || levels < 1)
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    if (target == GL_TEXTURE_CUBE_MAP && width != height)
    {
        return gl::error(GL_INVALID_VALUE, false);
    }

    if (levels != 1 && levels != gl::log2(std::max(width, height)) + 1)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    GLenum format = gl::GetFormat(internalformat, context->getClientVersion());
    GLenum type = gl::GetType(internalformat, context->getClientVersion());

    if (format == GL_NONE || type == GL_NONE)
    {
        return gl::error(GL_INVALID_ENUM, false);
    }

    switch (target)
    {
      case GL_TEXTURE_2D:
        if (width > context->getMaximum2DTextureDimension() ||
            height > context->getMaximum2DTextureDimension())
        {
            return gl::error(GL_INVALID_VALUE, false);
        }
        break;
      case GL_TEXTURE_CUBE_MAP:
        if (width > context->getMaximumCubeTextureDimension() ||
            height > context->getMaximumCubeTextureDimension())
        {
            return gl::error(GL_INVALID_VALUE, false);
        }
        break;
      default:
        return gl::error(GL_INVALID_ENUM, false);
    }

    if (levels != 1 && !context->supportsNonPower2Texture())
    {
        if (!gl::isPow2(width) || !gl::isPow2(height))
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }
    }

    switch (internalformat)
    {
      case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
      case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
        if (!context->supportsDXT1Textures())
        {
            return gl::error(GL_INVALID_ENUM, false);
        }
        break;
      case GL_COMPRESSED_RGBA_S3TC_DXT3_ANGLE:
        if (!context->supportsDXT3Textures())
        {
            return gl::error(GL_INVALID_ENUM, false);
        }
        break;
      case GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE:
        if (!context->supportsDXT5Textures())
        {
            return gl::error(GL_INVALID_ENUM, false);
        }
        break;
      case GL_RGBA32F_EXT:
      case GL_RGB32F_EXT:
      case GL_ALPHA32F_EXT:
      case GL_LUMINANCE32F_EXT:
      case GL_LUMINANCE_ALPHA32F_EXT:
        if (!context->supportsFloat32Textures())
        {
            return gl::error(GL_INVALID_ENUM, false);
        }
        break;
      case GL_RGBA16F_EXT:
      case GL_RGB16F_EXT:
      case GL_ALPHA16F_EXT:
      case GL_LUMINANCE16F_EXT:
      case GL_LUMINANCE_ALPHA16F_EXT:
        if (!context->supportsFloat16Textures())
        {
            return gl::error(GL_INVALID_ENUM, false);
        }
        break;
      case GL_DEPTH_COMPONENT16:
      case GL_DEPTH_COMPONENT32_OES:
      case GL_DEPTH24_STENCIL8_OES:
        if (!context->supportsDepthTextures())
        {
            return gl::error(GL_INVALID_ENUM, false);
        }
        if (target != GL_TEXTURE_2D)
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }
        // ANGLE_depth_texture only supports 1-level textures
        if (levels != 1)
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }
        break;
      default:
        break;
    }

    gl::Texture *texture = NULL;
    switch(target)
    {
      case GL_TEXTURE_2D:
        texture = context->getTexture2D();
        break;
      case GL_TEXTURE_CUBE_MAP:
        texture = context->getTextureCubeMap();
        break;
      default:
        UNREACHABLE();
    }

    if (!texture || texture->id() == 0)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    if (texture->isImmutable())
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    return true;
}

bool ValidateES2FramebufferTextureParameters(gl::Context *context, GLenum target, GLenum attachment,
                                             GLenum textarget, GLuint texture, GLint level)
{
    META_ASSERT(GL_DRAW_FRAMEBUFFER == GL_DRAW_FRAMEBUFFER_ANGLE && GL_READ_FRAMEBUFFER == GL_READ_FRAMEBUFFER_ANGLE);

    if (target != GL_FRAMEBUFFER && target != GL_DRAW_FRAMEBUFFER && target != GL_READ_FRAMEBUFFER)
    {
        return gl::error(GL_INVALID_ENUM, false);
    }

    if (attachment >= GL_COLOR_ATTACHMENT0 && attachment <= GL_COLOR_ATTACHMENT15)
    {
        const unsigned int colorAttachment = (attachment - GL_COLOR_ATTACHMENT0);
        if (colorAttachment >= context->getMaximumRenderTargets())
        {
            return gl::error(GL_INVALID_VALUE, false);
        }
    }
    else
    {
        switch (attachment)
        {
          case GL_DEPTH_ATTACHMENT:
          case GL_STENCIL_ATTACHMENT:
            break;
          default:
            return gl::error(GL_INVALID_ENUM, false);
        }
    }

    if (texture != 0)
    {
        gl::Texture *tex = context->getTexture(texture);

        if (tex == NULL)
        {
            return gl::error(GL_INVALID_OPERATION, false);
        }

        switch (textarget)
        {
          case GL_TEXTURE_2D:
            {
                if (tex->getTarget() != GL_TEXTURE_2D)
                {
                    return gl::error(GL_INVALID_OPERATION, false);
                }
                gl::Texture2D *tex2d = static_cast<gl::Texture2D *>(tex);
                if (tex2d->isCompressed(level))
                {
                    return gl::error(GL_INVALID_OPERATION, false);
                }
                break;
            }

          case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
          case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
          case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
          case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
          case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
          case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
            {
                if (tex->getTarget() != GL_TEXTURE_CUBE_MAP)
                {
                    return gl::error(GL_INVALID_OPERATION, false);
                }
                gl::TextureCubeMap *texcube = static_cast<gl::TextureCubeMap *>(tex);
                if (texcube->isCompressed(textarget, level))
                {
                    return gl::error(GL_INVALID_OPERATION, false);
                }
                break;
            }

          default:
            return gl::error(GL_INVALID_ENUM, false);
        }

        if (level != 0)
        {
            return gl::error(GL_INVALID_VALUE, false);
        }
    }

    gl::Framebuffer *framebuffer = NULL;
    GLuint framebufferHandle = 0;
    if (target == GL_READ_FRAMEBUFFER)
    {
        framebuffer = context->getReadFramebuffer();
        framebufferHandle = context->getReadFramebufferHandle();
    }
    else
    {
        framebuffer = context->getDrawFramebuffer();
        framebufferHandle = context->getDrawFramebufferHandle();
    }

    if (framebufferHandle == 0 || !framebuffer)
    {
        return gl::error(GL_INVALID_OPERATION, false);
    }

    return true;
}

// check for combinations of format and type that are valid for ReadPixels
bool ValidES2ReadFormatType(GLenum format, GLenum type)
{
    switch (format)
    {
      case GL_RGBA:
        switch (type)
        {
          case GL_UNSIGNED_BYTE:
            break;
          default:
            return false;
        }
        break;
      case GL_BGRA_EXT:
        switch (type)
        {
          case GL_UNSIGNED_BYTE:
          case GL_UNSIGNED_SHORT_4_4_4_4_REV_EXT:
          case GL_UNSIGNED_SHORT_1_5_5_5_REV_EXT:
            break;
          default:
            return false;
        }
        break;
      default:
        return false;
    }
    return true;
}

}