Kotlin/Native C Interop - Usage in Kotlin class

App.def

headers = nuklear.h App.h nuklear_glfw_gl2.h nk_defines.h /usr/include/GLFW/glfw3.h /usr/include/GLFW/glfw3native.h
compiler-options = -framework OpenGl
package = glfw
linkerOpts.osx = -L/opt/local/lib -L/usr/local/lib -lglfw
linkerOpts.linux = -L/usr/lib64 -L/usr/lib/x86_64-linux-gnu -lglfw -lGLU -lGL -lglut
linkerOpts.mingw = -lglfw

build.gradle.kts

plugins {
    kotlin("multiplatform") version "1.5.31"
}

group = "me.sudharsanarajalingam"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}
allprojects {
    configurations {
        all {
            resolutionStrategy {
                force("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.2-native-mt")
            }
        }
    }
}
kotlin {
    val hostOs = System.getProperty("os.name")
    val isMingwX64 = hostOs.startsWith("Windows")
    val nativeTarget = when {
        hostOs == "Mac OS X" -> macosX64("native")
        hostOs == "Linux" -> linuxX64("native")
        isMingwX64 -> mingwX64("native")
        else -> throw GradleException("Host OS is not supported in Kotlin/Native.")
    }
  //  val main by compilations.getting
   // val interop by main.cinterops.creating
    nativeTarget.apply {
        val main by compilations.getting
        main.cinterops.create("applib") {
            defFile(project.file("src/nativeInterop/cinterop/App.def"))
            packageName ("com.myapp.applib")
            compilerOpts ("-I/src/nativeInterop/cinterop")
            linkerOpts ("-I/src/nativeInterop/cinterop")
            // 3
            includeDirs{
            //    allHeaders ("src/nativeInterop/cinterop","/Library/Developer/glfw/include/GLFW")
            allHeaders("/usr/include","src/nativeInterop/cinterop")
            }
        }

        binaries {
            executable {
                entryPoint = "main"
            }
        }
    }

    sourceSets {
        val nativeMain by getting {
            dependencies {
                implementation("io.ktor:ktor-client-curl:1.6.3")
                implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.2-native-mt")
                // df
            }

        }
        val nativeTest by getting
    }
}

main.kt

import com.myapp.applib.*
import kotlinx.cinterop.*
import kotlinx.cinterop.nativeHeap.alloc
import platform.posix.exit
import platform.posix.fprintf
import platform.posix.stdout
import kotlinx.cinterop.*
import interop.*


fun main() {


    var ctx: CPointer<nk_context>? = null
    var bg: nk_colorf
    val width = 0
    val height = 0

    var glfwInitialized = glfwInit()
    if (glfwInitialized == 0) {
        println("Failed to initialize GLFW")
        return
    }
    var window = glfwCreateWindow(640, 480, "OpenGL on Kotlin! Wow!", null, null);
    if (window == null)
    {
        println("Failed to create GLFW window")
        glfwTerminate()
        return
    }

    println("hello world! glfw initialized? = $glfwInitialized, window pointer = $window")
    glfwMakeContextCurrent(window)

    ctx = nk_glfw3_init(window, NK_GLFW3_INSTALL_CALLBACKS)

    
    while(glfwWindowShouldClose(window) == 0)
    {
        glClear(GL_COLOR_BUFFER_BIT)
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    glfwTerminate()
}

nk_defines.h

#include <stdio.h>

#define NK_INCLUDE_FIXED_TYPES
#define NK_INCLUDE_STANDARD_IO
#define NK_INCLUDE_STANDARD_VARARGS
#define NK_INCLUDE_DEFAULT_ALLOCATOR
#define NK_INCLUDE_VERTEX_BUFFER_OUTPUT
#define NK_INCLUDE_FONT_BAKING
#define NK_INCLUDE_DEFAULT_FONT
#define NK_IMPLEMENTATION
#define NK_GLFW_GL2_IMPLEMENTATION
#define NK_KEYSTATE_BASED_INPUT

static void error_callback(int e, const char *d)
{
    printf("Error %d: %s\n", e, d);
}

nuklear headers

https://github.com/Immediate-Mode-UI/Nuklear/tree/master/demo/glfw_opengl2

https://github.com/Immediate-Mode-UI/Nuklear/blob/master/nuklear.h