glTextureStorage2D

glTexStorage2D: man4/glTexStorage2D.xml

glTexStorage2D and glTextureStorage2D specify the storage requirements for all levels of a two-dimensional texture or one-dimensional texture array simultaneously. Once a texture is specified with this command, the format and dimensions of all levels become immutable unless it is a proxy texture. The contents of the image may still be modified, however, its storage requirements may not change. Such a texture is referred to as an texture. The behavior of glTexStorage2D depends on the target parameter. When target is GL_TEXTURE_2D, GL_PROXY_TEXTURE_2D, GL_TEXTURE_RECTANGLE, GL_PROXY_TEXTURE_RECTANGLE or GL_PROXY_TEXTURE_CUBE_MAP, calling glTexStorage2D is equivalent, assuming no errors are generated, to executing the following pseudo-code:

for (i = 0; i < levels; i++) {
    glTexImage2D(target, i, internalformat, width, height, 0, format, type, NULL);
    width = max(1, (width / 2));
    height = max(1, (height / 2));
}

When target is GL_TEXTURE_CUBE_MAP, glTexStorage2D is equivalent to:

for (i = 0; i < levels; i++) {
    for (face in (+X, -X, +Y, -Y, +Z, -Z)) {
        glTexImage2D(face, i, internalformat, width, height, 0, format, type, NULL);
    }
    width = max(1, (width / 2));
    height = max(1, (height / 2));
}

When target is GL_TEXTURE_1D or GL_TEXTURE_1D_ARRAY, glTexStorage2D is equivalent to:

for (i = 0; i < levels; i++) {
    glTexImage2D(target, i, internalformat, width, height, 0, format, type, NULL);
    width = max(1, (width / 2));
}

Calling glTextureStorage2D is equivalent to the above pseudo-code, where target is the effective target of texture and it is as if texture were bound to target for the purposes of glTexImage2D. Since no texture data is actually provided, the values used in the pseudo-code for format and type are irrelevant and may be considered to be any values that are legal for the chosen internalformat enumerant. internalformat must be one of the sized internal formats given in Table 1 below, one of the sized depth-component formats GL_DEPTH_COMPONENT32F, GL_DEPTH_COMPONENT24, or GL_DEPTH_COMPONENT16, one of the combined depth-stencil formats, GL_DEPTH32F_STENCIL8, or GL_DEPTH24_STENCIL8, or the stencil-only format, GL_STENCIL_INDEX8. Upon success, the value of GL_TEXTURE_IMMUTABLE_FORMAT becomes GL_TRUE. The value of GL_TEXTURE_IMMUTABLE_FORMAT may be discovered by calling glGetTexParameter with pname set to GL_TEXTURE_IMMUTABLE_FORMAT. No further changes to the dimensions or format of the texture object may be made. Using any command that might alter the dimensions or format of the texture object (such as glTexImage2D or another call to glTexStorage2D ) will result in the generation of a GL_INVALID_OPERATION error, even if it would not, in fact, alter the dimensions or format of the object.<h3> Sized Internal Formats</h3> Sized Internal Format Base Internal Format Red Bits Green Bits Blue Bits Alpha Bits Shared Bits GL_R8 GL_RED 8 GL_R8_SNORM GL_RED s8 GL_R16 GL_RED 16 GL_R16_SNORM GL_RED s16 GL_RG8 GL_RG 8 8 GL_RG8_SNORM GL_RG s8 s8 GL_RG16 GL_RG 16 16 GL_RG16_SNORM GL_RG s16 s16 GL_R3_G3_B2 GL_RGB 3 3 2 GL_RGB4 GL_RGB 4 4 4 GL_RGB5 GL_RGB 5 5 5 GL_RGB8 GL_RGB 8 8 8 GL_RGB8_SNORM GL_RGB s8 s8 s8 GL_RGB10 GL_RGB 10 10 10 GL_RGB12 GL_RGB 12 12 12 GL_RGB16_SNORM GL_RGB 16 16 16 GL_RGBA2 GL_RGB 2 2 2 2 GL_RGBA4 GL_RGB 4 4 4 4 GL_RGB5_A1 GL_RGBA 5 5 5 1 GL_RGBA8 GL_RGBA 8 8 8 8 GL_RGBA8_SNORM GL_RGBA s8 s8 s8 s8 GL_RGB10_A2 GL_RGBA 10 10 10 2 GL_RGB10_A2UI GL_RGBA ui10 ui10 ui10 ui2 GL_RGBA12 GL_RGBA 12 12 12 12 GL_RGBA16 GL_RGBA 16 16 16 16 GL_SRGB8 GL_RGB 8 8 8 GL_SRGB8_ALPHA8 GL_RGBA 8 8 8 8 GL_R16F GL_RED f16 GL_RG16F GL_RG f16 f16 GL_RGB16F GL_RGB f16 f16 f16 GL_RGBA16F GL_RGBA f16 f16 f16 f16 GL_R32F GL_RED f32 GL_RG32F GL_RG f32 f32 GL_RGB32F GL_RGB f32 f32 f32 GL_RGBA32F GL_RGBA f32 f32 f32 f32 GL_R11F_G11F_B10F GL_RGB f11 f11 f10 GL_RGB9_E5 GL_RGB 9 9 9 5 GL_R8I GL_RED i8 GL_R8UI GL_RED ui8 GL_R16I GL_RED i16 GL_R16UI GL_RED ui16 GL_R32I GL_RED i32 GL_R32UI GL_RED ui32 GL_RG8I GL_RG i8 i8 GL_RG8UI GL_RG ui8 ui8 GL_RG16I GL_RG i16 i16 GL_RG16UI GL_RG ui16 ui16 GL_RG32I GL_RG i32 i32 GL_RG32UI GL_RG ui32 ui32 GL_RGB8I GL_RGB i8 i8 i8 GL_RGB8UI GL_RGB ui8 ui8 ui8 GL_RGB16I GL_RGB i16 i16 i16 GL_RGB16UI GL_RGB ui16 ui16 ui16 GL_RGB32I GL_RGB i32 i32 i32 GL_RGB32UI GL_RGB ui32 ui32 ui32 GL_RGBA8I GL_RGBA i8 i8 i8 i8 GL_RGBA8UI GL_RGBA ui8 ui8 ui8 ui8 GL_RGBA16I GL_RGBA i16 i16 i16 i16 GL_RGBA16UI GL_RGBA ui16 ui16 ui16 ui16 GL_RGBA32I GL_RGBA i32 i32 i32 i32 GL_RGBA32UI GL_RGBA ui32 ui32 ui32 ui32

GL_STENCIL_INDEX8 is accepted for internalformat only if the GL version is 4.4 or higher.