glClearColor

// OPENGL32.dll
#include <windows.h>

void glClearColor(
    FLOAT red,
    FLOAT green,
    FLOAT blue,
    FLOAT alpha
);

<DllImport("OPENGL32.dll", ExactSpelling:=True)>
Public Shared Sub glClearColor(
    red As Single,   ' FLOAT
    green As Single,   ' FLOAT
    blue As Single,   ' FLOAT
    alpha As Single   ' FLOAT
)
End Sub

' red : FLOAT
' green : FLOAT
' blue : FLOAT
' alpha : FLOAT
Declare PtrSafe Sub glClearColor Lib "opengl32" ( _
    ByVal red As Single, _
    ByVal green As Single, _
    ByVal blue As Single, _
    ByVal alpha As Single)
' VBA7前提(PtrSafe)。32bit Office では LongPtr→Long。Integer=16bit / Long=32bit / LongLong=64bit。

import ctypes
from ctypes import wintypes

glClearColor = ctypes.windll.opengl32.glClearColor
glClearColor.restype = None
glClearColor.argtypes = [
    ctypes.c_float,  # red : FLOAT
    ctypes.c_float,  # green : FLOAT
    ctypes.c_float,  # blue : FLOAT
    ctypes.c_float,  # alpha : FLOAT
]

require 'fiddle'
require 'fiddle/import'

lib = Fiddle.dlopen('OPENGL32.dll')
glClearColor = Fiddle::Function.new(
  lib['glClearColor'],
  [
    Fiddle::TYPE_FLOAT,  # red : FLOAT
    Fiddle::TYPE_FLOAT,  # green : FLOAT
    Fiddle::TYPE_FLOAT,  # blue : FLOAT
    Fiddle::TYPE_FLOAT,  # alpha : FLOAT
  ],
  Fiddle::TYPE_VOID)

#[link(name = "opengl32")]
extern "system" {
    fn glClearColor(
        red: f32,  // FLOAT
        green: f32,  // FLOAT
        blue: f32,  // FLOAT
        alpha: f32  // FLOAT
    );
}
// crates: windows-sys provides ready-made bindings for this API.

$sig = @"
[DllImport("OPENGL32.dll")]
public static extern void glClearColor(float red, float green, float blue, float alpha);
"@
$api = Add-Type -MemberDefinition $sig -Name 'OPENGL32_glClearColor' -Namespace Win32 -PassThru
# $api::glClearColor(red, green, blue, alpha)

#uselib "OPENGL32.dll"
#func global glClearColor "glClearColor" float, float, float, float
; glClearColor red, green, blue, alpha
; red : FLOAT -> "float"
; green : FLOAT -> "float"
; blue : FLOAT -> "float"
; alpha : FLOAT -> "float"

#uselib "OPENGL32.dll"
#func global glClearColor "glClearColor" float, float, float, float
; glClearColor red, green, blue, alpha
; red : FLOAT -> "float"
; green : FLOAT -> "float"
; blue : FLOAT -> "float"
; alpha : FLOAT -> "float"

; void glClearColor(FLOAT red, FLOAT green, FLOAT blue, FLOAT alpha)
#uselib "OPENGL32.dll"
#func global glClearColor "glClearColor" float, float, float, float
; glClearColor red, green, blue, alpha
; red : FLOAT -> "float"
; green : FLOAT -> "float"
; blue : FLOAT -> "float"
; alpha : FLOAT -> "float"

import (
	"math"
	"golang.org/x/sys/windows"
	"unsafe"
)

var (
	opengl32 = windows.NewLazySystemDLL("OPENGL32.dll")
	procglClearColor = opengl32.NewProc("glClearColor")
)

// red (FLOAT), green (FLOAT), blue (FLOAT), alpha (FLOAT)
r1, _, err := procglClearColor.Call(
	uintptr(math.Float32bits(red)),
	uintptr(math.Float32bits(green)),
	uintptr(math.Float32bits(blue)),
	uintptr(math.Float32bits(alpha)),
)
_ = err  // syscall.Errno (valid when the call sets last-error)
_ = r1   // void
// 注意: float/double 引数は proc.Call では XMM レジスタに渡せません。
// windows.SyscallN(proc.Addr(), math.Float64bits(x), ...) もしくは cgo を使用してください。

procedure glClearColor(
  red: Single;   // FLOAT
  green: Single;   // FLOAT
  blue: Single;   // FLOAT
  alpha: Single   // FLOAT
); stdcall;
  external 'OPENGL32.dll' name 'glClearColor';

result := DllCall("OPENGL32\glClearColor"
    , "Float", red   ; FLOAT
    , "Float", green   ; FLOAT
    , "Float", blue   ; FLOAT
    , "Float", alpha   ; FLOAT
    , "Int")   ; return: void

●glClearColor(red, green, blue, alpha) = DLL("OPENGL32.dll", "int glClearColor(float, float, float, float)")
# 呼び出し: glClearColor(red, green, blue, alpha)
# red : FLOAT -> "float"
# green : FLOAT -> "float"
# blue : FLOAT -> "float"
# alpha : FLOAT -> "float"
# なでしこ1は32bit・ANSI(Shift_JIS)。文字列=char*(ANSI)、ポインタ/ハンドル=void*(4byte)。