glium 0.34.0

Elegant and safe OpenGL wrapper. Glium is an intermediate layer between OpenGL and your application. You still need to manually handle the graphics pipeline, but without having to use OpenGL's old and error-prone API. Its objectives: - Be safe to use. Many aspects of OpenGL that can trigger a crash if misused are automatically handled by glium. - Provide an API that enforces good pratices such as RAII or stateless function calls. - Be compatible with all OpenGL versions that support shaders, providing unified API when things diverge. - Avoid all OpenGL errors beforehand. - Produce optimized OpenGL function calls, and allow the user to easily use modern OpenGL techniques.
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use crate::context::CommandContext;
use crate::version::Version;
use crate::version::Api;
use crate::gl;

use std::fmt;
use std::error::Error;

use crate::texture::any::TextureAny;
use crate::TextureExt;
use crate::GlObject;

/// Error that can happen when retrieving the internal format of a texture.
#[derive(Copy, Clone, Debug)]
pub enum GetFormatError {
    /// The backend doesn't support retrieving the internal format.
    NotSupported,
}

impl fmt::Display for GetFormatError {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        use self::GetFormatError::*;
        let desc = match self {
            NotSupported => "The backend doesn't support retrieving the internal format",
        };
        fmt.write_str(desc)
    }
}

impl Error for GetFormatError {}

/// Internal format of a texture.
///
/// The actual format of a texture is not necessarily one of the predefined ones, so we have
/// to use a very generic description.
// TODO: change bits to be u16 for consistency with the rest of the library
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum InternalFormat {
    /// The format has one component.
    OneComponent {
        /// Type of the first component of the format.
        ty1: InternalFormatType,
        /// Number of bits of the first component.
        bits1: usize,
    },

    /// The format has two components.
    TwoComponents {
        /// Type of the first component of the format.
        ty1: InternalFormatType,
        /// Number of bits of the first component.
        bits1: usize,
        /// Type of the second component.
        ty2: InternalFormatType,
        /// Number of bits of the second component.
        bits2: usize,
    },

    /// The format has three components.
    ThreeComponents {
        /// Type of the first component of the format.
        ty1: InternalFormatType,
        /// Number of bits of the first component.
        bits1: usize,
        /// Type of the second component.
        ty2: InternalFormatType,
        /// Number of bits of the second component.
        bits2: usize,
        /// Type of the third component.
        ty3: InternalFormatType,
        /// Number of bits of the third component.
        bits3: usize,
    },

    /// The format has four components.
    FourComponents {
        /// Type of the first component of the format.
        ty1: InternalFormatType,
        /// Number of bits of the first component.
        bits1: usize,
        /// Type of the second component.
        ty2: InternalFormatType,
        /// Number of bits of the second component.
        bits2: usize,
        /// Type of the third component.
        ty3: InternalFormatType,
        /// Number of bits of the third component.
        bits3: usize,
        /// Type of the fourth component.
        ty4: InternalFormatType,
        /// Number of bits of the fourth component.
        bits4: usize,
    },
}

impl InternalFormat {
    /// Returns the total number of bits of this format.
    #[inline]
    pub fn get_total_bits(&self) -> usize {
        match *self {
            InternalFormat::OneComponent { bits1, .. } => bits1,
            InternalFormat::TwoComponents { bits1, bits2, .. } => bits1 + bits2,
            InternalFormat::ThreeComponents { bits1, bits2, bits3, .. } => bits1 + bits2 + bits3,
            InternalFormat::FourComponents { bits1, bits2, bits3, bits4, .. } =>
                                                                    bits1 + bits2 + bits3 + bits4,
        }
    }
}

/// Format of a component of an internal format.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum InternalFormatType {
    /// Floating point texture with signed components.
    SignedNormalized,
    /// Floating point texture with unsigned components.
    UnsignedNormalized,
    /// Floating point texture with floats.
    Float,
    /// Integral texture.
    Int,
    /// Unsigned texture.
    UnsignedInt,
}

impl InternalFormatType {
    /// Builds the `InternalFormatType` of the GLenum. Panics if the value is not recognized.
    #[inline]
    fn from_glenum(val: gl::types::GLenum) -> InternalFormatType {
        match val {
            gl::SIGNED_NORMALIZED => InternalFormatType::SignedNormalized,
            gl::UNSIGNED_NORMALIZED => InternalFormatType::UnsignedNormalized,
            gl::FLOAT => InternalFormatType::Float,
            gl::INT => InternalFormatType::Int,
            gl::UNSIGNED_INT => InternalFormatType::UnsignedInt,
            gl::NONE => unreachable!(),     // separating this case for easier debugging
            _ => unreachable!(),
        }
    }
}

/// Determines the format of a texture.
///
/// A `TextureAny` is guaranteed to have the same format for each mipmap.
pub fn get_format(ctxt: &mut CommandContext<'_>, texture: &TextureAny)
                  -> Result<InternalFormat, GetFormatError>
{
    if ctxt.version >= &Version(Api::Gl, 3, 0) || ctxt.version >= &Version(Api::GlEs, 3, 0) {
        let (red_sz, red_ty, green_sz, green_ty, blue_sz, blue_ty,
             alpha_sz, alpha_ty, depth_sz, depth_ty) = unsafe
        {
            let mut red_sz = 0;
            let mut red_ty = 0;
            let mut green_sz = 0;
            let mut green_ty = 0;
            let mut blue_sz = 0;
            let mut blue_ty = 0;
            let mut alpha_sz = 0;
            let mut alpha_ty = 0;
            let mut depth_sz = 0;
            let mut depth_ty = 0;

            if ctxt.version >= &Version(Api::Gl, 4, 5) ||
               ctxt.extensions.gl_arb_direct_state_access
            {
                let id = texture.get_id();
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_RED_SIZE, &mut red_sz);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_RED_TYPE, &mut red_ty);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_GREEN_SIZE, &mut green_sz);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_GREEN_TYPE, &mut green_ty);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_BLUE_SIZE, &mut blue_sz);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_BLUE_TYPE, &mut blue_ty);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_ALPHA_SIZE, &mut alpha_sz);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_ALPHA_TYPE, &mut alpha_ty);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_DEPTH_SIZE, &mut depth_sz);
                ctxt.gl.GetTextureLevelParameteriv(id, 0, gl::TEXTURE_DEPTH_TYPE, &mut depth_ty);

            } else if ctxt.extensions.gl_ext_direct_state_access {
                let id = texture.get_id();
                let bind_point = texture.get_bind_point();

                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_RED_SIZE,
                                                      &mut red_sz);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_RED_TYPE,
                                                      &mut red_ty);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_GREEN_SIZE,
                                                      &mut green_sz);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_GREEN_TYPE,
                                                      &mut green_ty);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_BLUE_SIZE,
                                                      &mut blue_sz);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_BLUE_TYPE,
                                                      &mut blue_ty);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_ALPHA_SIZE,
                                                      &mut alpha_sz);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_ALPHA_TYPE,
                                                      &mut alpha_ty);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_DEPTH_SIZE,
                                                      &mut depth_sz);
                ctxt.gl.GetTextureLevelParameterivEXT(id, bind_point, 0, gl::TEXTURE_DEPTH_TYPE,
                                                      &mut depth_ty);

            } else {
                let bind_point = texture.bind_to_current(ctxt);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_RED_SIZE, &mut red_sz);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_RED_TYPE, &mut red_ty);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_GREEN_SIZE,
                                               &mut green_sz);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_GREEN_TYPE,
                                               &mut green_ty);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_BLUE_SIZE, &mut blue_sz);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_BLUE_TYPE, &mut blue_ty);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_ALPHA_SIZE,
                                               &mut alpha_sz);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_ALPHA_TYPE,
                                               &mut alpha_ty);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_DEPTH_SIZE,
                                               &mut depth_sz);
                ctxt.gl.GetTexLevelParameteriv(bind_point, 0, gl::TEXTURE_DEPTH_TYPE,
                                               &mut depth_ty);
            }

            (red_sz as gl::types::GLenum, red_ty as gl::types::GLenum,
             green_sz as gl::types::GLenum, green_ty as gl::types::GLenum,
             blue_sz as gl::types::GLenum, blue_ty as gl::types::GLenum,
             alpha_sz as gl::types::GLenum, alpha_ty as gl::types::GLenum,
             depth_sz as gl::types::GLenum, depth_ty as gl::types::GLenum)
        };

        Ok(match (red_sz, red_ty, green_sz, green_ty, blue_sz, blue_ty,
               alpha_sz, alpha_ty, depth_sz, depth_ty)
        {
            (_, gl::NONE, _, _, _, _, _, _, _, gl::NONE) => return Err(GetFormatError::NotSupported),
            (_, gl::NONE, _, _, _, _, _, _, sz1, ty1) => InternalFormat::OneComponent {
                ty1: InternalFormatType::from_glenum(ty1),
                bits1: sz1 as usize,
            },
            (sz1, ty1, _, gl::NONE, _, _, _, _, _, _) => InternalFormat::OneComponent {
                ty1: InternalFormatType::from_glenum(ty1),
                bits1: sz1 as usize,
            },
            (sz1, ty1, sz2, ty2, _, gl::NONE, _, _, _, _) => InternalFormat::TwoComponents {
                ty1: InternalFormatType::from_glenum(ty1),
                bits1: sz1 as usize,
                ty2: InternalFormatType::from_glenum(ty2),
                bits2: sz2 as usize,
            },
            (sz1, ty1, sz2, ty2, sz3, ty3, _, gl::NONE, _, _) => InternalFormat::ThreeComponents {
                ty1: InternalFormatType::from_glenum(ty1),
                bits1: sz1 as usize,
                ty2: InternalFormatType::from_glenum(ty2),
                bits2: sz2 as usize,
                ty3: InternalFormatType::from_glenum(ty3),
                bits3: sz3 as usize,
            },
            (sz1, ty1, sz2, ty2, sz3, ty3, sz4, ty4, _, gl::NONE) => InternalFormat::FourComponents {
                ty1: InternalFormatType::from_glenum(ty1),
                bits1: sz1 as usize,
                ty2: InternalFormatType::from_glenum(ty2),
                bits2: sz2 as usize,
                ty3: InternalFormatType::from_glenum(ty3),
                bits3: sz3 as usize,
                ty4: InternalFormatType::from_glenum(ty4),
                bits4: sz4 as usize,
            },
            _ => unreachable!()
        })

    } else {
        // FIXME: GL2
        Err(GetFormatError::NotSupported)
    }
}