impeller::SamplerGLES Class Reference

#include <sampler_gles.h>

Inheritance diagram for impeller::SamplerGLES:

Public Member Functions
	~SamplerGLES ()
bool	ConfigureBoundTexture (const TextureGLES &texture, const ProcTableGLES &gl) const
Public Member Functions inherited from impeller::Sampler
virtual	~Sampler ()
const SamplerDescriptor &	GetDescriptor () const

Friends
class	SamplerLibraryGLES

Additional Inherited Members
Static Public Member Functions inherited from impeller::BackendCast< SamplerGLES, Sampler >
static SamplerGLES &	Cast (Sampler &base)
static const SamplerGLES &	Cast (const Sampler &base)
static SamplerGLES *	Cast (Sampler *base)
static const SamplerGLES *	Cast (const Sampler *base)
Protected Member Functions inherited from impeller::Sampler
	Sampler (const SamplerDescriptor &desc)
Protected Attributes inherited from impeller::Sampler
SamplerDescriptor	desc_

Detailed Description

Definition at line 17 of file sampler_gles.h.

Constructor & Destructor Documentation

~SamplerGLES()

impeller::SamplerGLES::~SamplerGLES ( )

default

Member Function Documentation

ConfigureBoundTexture()

bool impeller::SamplerGLES::ConfigureBoundTexture	(	const TextureGLES &	texture,
		const ProcTableGLES &	gl
	)		const

Definition at line 72 of file sampler_gles.cc.

                                                                       {
  auto target = ToTextureTarget(texture.GetTextureDescriptor().type);
 
  if (!target.has_value()) {
    return false;
  }
  const SamplerDescriptor& desc = GetDescriptor();
 
  GLint mag_filter = ToParam(desc.mag_filter);
 
  // If the texture doesn't have mipmaps, we can't use mip filtering.
  GLint min_filter;
  if (texture.GetTextureDescriptor().mip_count > 1) {
    min_filter = ToParam(desc.min_filter, desc.mip_filter);
  } else {
    min_filter = ToParam(desc.min_filter);
  }
 
  gl.TexParameteri(*target, GL_TEXTURE_MIN_FILTER, min_filter);
  gl.TexParameteri(*target, GL_TEXTURE_MAG_FILTER, mag_filter);
 
  // Bound the sampled mip range to the levels the texture declares. GLES leaves
  // GL_TEXTURE_MAX_LEVEL at its default of 1000, so a texture sampled with a
  // mipmap filter reads as black unless every level down to 1x1 is defined.
  // Metal and Vulkan allocate exactly mip_count levels, and clamping here gives
  // the same behavior for a partial, manually uploaded mip chain. The parameter
  // is unavailable on ES 2.0 without GL_APPLE_texture_max_level, and external
  // textures have no mip levels, so it is skipped in those cases.
  if (*target != GL_TEXTURE_EXTERNAL_OES &&
      gl.GetCapabilities()->SupportsTextureMaxLevel()) {
    const GLint max_level =
        static_cast<GLint>(texture.GetTextureDescriptor().mip_count) - 1;
    gl.TexParameteri(*target, GL_TEXTURE_MAX_LEVEL, max_level);
  }
 
  const auto supports_decal_mode =
      gl.GetCapabilities()->SupportsDecalSamplerAddressMode();
 
  const auto wrap_s =
      ToAddressMode(desc.width_address_mode, supports_decal_mode);
  const auto wrap_t =
      ToAddressMode(desc.height_address_mode, supports_decal_mode);
 
  gl.TexParameteri(*target, GL_TEXTURE_WRAP_S, wrap_s);
  gl.TexParameteri(*target, GL_TEXTURE_WRAP_T, wrap_t);
 
  if (wrap_s == IMPELLER_GL_CLAMP_TO_BORDER ||
      wrap_t == IMPELLER_GL_CLAMP_TO_BORDER) {
    // Transparent black.
    const GLfloat border_color[4] = {0.0f, 0.0f, 0.0f, 0.0f};
    gl.TexParameterfv(*target, IMPELLER_GL_TEXTURE_BORDER_COLOR, border_color);
  }
 
  // Anisotropy is a per-texture parameter in GLES, so it must be written on
  // every configuration (including resetting it back to 1) to prevent a
  // previously configured value from leaking into this sampler's state. The
  // parameter only exists when GL_EXT_texture_filter_anisotropic is present;
  // it is applied with TexParameterfv, which is core ES 2.0.
  const uint32_t max_anisotropy =
      gl.GetCapabilities()->GetMaxSamplerAnisotropy();
  if (max_anisotropy > 1) {
    const GLfloat anisotropy[1] = {static_cast<GLfloat>(
        std::clamp<uint32_t>(desc.max_anisotropy, 1u, max_anisotropy))};
    gl.TexParameterfv(*target, IMPELLER_GL_TEXTURE_MAX_ANISOTROPY, anisotropy);
  }
 
  return true;
}

References impeller::ProcTableGLES::GetCapabilities(), impeller::Texture::GetTextureDescriptor(), impeller::SamplerDescriptor::height_address_mode, IMPELLER_GL_CLAMP_TO_BORDER, IMPELLER_GL_TEXTURE_BORDER_COLOR, IMPELLER_GL_TEXTURE_MAX_ANISOTROPY, impeller::SamplerDescriptor::mag_filter, impeller::SamplerDescriptor::max_anisotropy, impeller::SamplerDescriptor::min_filter, impeller::TextureDescriptor::mip_count, impeller::SamplerDescriptor::mip_filter, impeller::ToAddressMode(), impeller::ToParam(), impeller::ToTextureTarget(), impeller::TextureDescriptor::type, and impeller::SamplerDescriptor::width_address_mode.

Friends And Related Function Documentation

SamplerLibraryGLES

friend class SamplerLibraryGLES

friend

Definition at line 26 of file sampler_gles.h.

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The documentation for this class was generated from the following files:

• impeller/renderer/backend/gles/sampler_gles.h
• impeller/renderer/backend/gles/sampler_gles.cc