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|
use std::ffi::{c_int, c_void};
use std::mem::size_of;
use safer_ffi::layout::ReprC;
use crate::buffer::Buffer;
use crate::CurrentContextWithFns;
#[derive(Debug)]
pub struct VertexArray
{
array: crate::sys::types::GLuint,
}
impl VertexArray
{
#[must_use]
pub fn new(current_context: &CurrentContextWithFns<'_>) -> Self
{
let mut array = 0;
unsafe {
current_context.fns().CreateVertexArrays(1, &raw mut array);
}
Self { array }
}
/// Draws the currently bound vertex array.
///
/// # Errors
/// Returns `Err` if:
/// - `start_index` is too large
/// - `cnt` is too large
pub fn draw_arrays(
current_context: &CurrentContextWithFns<'_>,
primitive_kind: PrimitiveKind,
start_index: u32,
cnt: u32,
) -> Result<(), DrawError>
{
let start_index: crate::sys::types::GLint =
start_index
.try_into()
.map_err(|_| DrawError::StartIndexValueTooLarge {
value: start_index,
max_value: crate::sys::types::GLint::MAX as u32,
})?;
let cnt: crate::sys::types::GLsizei =
cnt.try_into().map_err(|_| DrawError::CountValueTooLarge {
value: cnt,
max_value: crate::sys::types::GLsizei::MAX as u32,
})?;
unsafe {
current_context
.fns()
.DrawArrays(primitive_kind.into_gl(), start_index, cnt);
}
Ok(())
}
/// Draws the currently bound vertex array.
///
/// # Errors
/// Returns `Err` if `cnt` is too large.
pub fn draw_elements(
current_context: &CurrentContextWithFns<'_>,
primitive_kind: PrimitiveKind,
start_index: u32,
cnt: u32,
) -> Result<(), DrawError>
{
let cnt: crate::sys::types::GLsizei =
cnt.try_into().map_err(|_| DrawError::CountValueTooLarge {
value: cnt,
max_value: crate::sys::types::GLsizei::MAX as u32,
})?;
unsafe {
current_context.fns().DrawElements(
primitive_kind.into_gl(),
cnt,
crate::sys::UNSIGNED_INT,
// TODO: Make this not sometimes UB. DrawElements expects a actual
// pointer to a memory location when no VBO is bound.
// See: https://stackoverflow.com/q/21706113
std::ptr::without_provenance::<c_void>(start_index as usize),
);
}
Ok(())
}
pub fn bind_element_buffer(
&self,
current_context: &CurrentContextWithFns<'_>,
element_buffer: &Buffer<u32>,
)
{
unsafe {
current_context
.fns()
.VertexArrayElementBuffer(self.array, element_buffer.object());
}
}
pub fn bind_vertex_buffer<VertexT: ReprC>(
&self,
current_context: &CurrentContextWithFns<'_>,
binding_index: u32,
vertex_buffer: &Buffer<VertexT>,
offset: isize,
)
{
let vertex_size = const { cast_usize_to_c_int(size_of::<VertexT>()) };
unsafe {
current_context.fns().VertexArrayVertexBuffer(
self.array,
binding_index,
vertex_buffer.object(),
offset,
vertex_size,
);
}
}
pub fn enable_attrib(
&self,
current_context: &CurrentContextWithFns<'_>,
attrib_index: u32,
)
{
unsafe {
current_context.fns().EnableVertexArrayAttrib(
self.array,
attrib_index as crate::sys::types::GLuint,
);
}
}
pub fn set_attrib_format(
&self,
current_context: &CurrentContextWithFns<'_>,
attrib_index: u32,
data_type: DataType,
normalized: bool,
offset: u32,
)
{
unsafe {
current_context.fns().VertexArrayAttribFormat(
self.array,
attrib_index,
data_type.size(),
data_type as u32,
if normalized {
crate::sys::TRUE
} else {
crate::sys::FALSE
},
offset,
);
}
}
/// Associate a vertex attribute and a vertex buffer binding.
pub fn set_attrib_vertex_buf_binding(
&self,
current_context: &CurrentContextWithFns<'_>,
attrib_index: u32,
vertex_buf_binding_index: u32,
)
{
unsafe {
current_context.fns().VertexArrayAttribBinding(
self.array,
attrib_index,
vertex_buf_binding_index,
);
}
}
pub fn bind(&self, current_context: &CurrentContextWithFns<'_>)
{
unsafe { current_context.fns().BindVertexArray(self.array) }
}
}
#[derive(Debug)]
pub enum PrimitiveKind
{
Triangles,
}
impl PrimitiveKind
{
fn into_gl(self) -> crate::sys::types::GLenum
{
match self {
Self::Triangles => crate::sys::TRIANGLES,
}
}
}
#[derive(Debug, Clone, Copy)]
#[repr(u32)]
pub enum DataType
{
Float = crate::sys::FLOAT,
}
impl DataType
{
fn size(self) -> crate::sys::types::GLint
{
match self {
Self::Float => const { cast_usize_to_c_int(size_of::<f32>()) },
}
}
}
#[derive(Debug, thiserror::Error)]
pub enum DrawError
{
#[error("Start index value {value} is too large. Must be < {max_value}")]
StartIndexValueTooLarge
{
value: u32, max_value: u32
},
#[error("Count value {value} is too large. Must be < {max_value}")]
CountValueTooLarge
{
value: u32, max_value: u32
},
}
const fn cast_usize_to_c_int(num: usize) -> c_int
{
assert!(num <= c_int::MAX.cast_unsigned() as usize);
c_int::from_ne_bytes(shorten_byte_array(num.to_ne_bytes()))
}
const fn shorten_byte_array<const SRC_LEN: usize, const DST_LEN: usize>(
src: [u8; SRC_LEN],
) -> [u8; DST_LEN]
{
assert!(DST_LEN < SRC_LEN);
let mut ret = [0; DST_LEN];
ret.copy_from_slice(src.split_at(DST_LEN).0);
ret
}
|
