Add createBuffer() and createTexture().

Also, I had mistakenly(?) thought when `gen___` returned a 0 it should be
treated as a `null`, but I can't find any reference to that in OpenGL docs,
so removed some checks.

kgl-android/src/main/kotlin/com/danielgergely/kgl/KglAndroid.kt

@@ -50,6 +50,13 @@ class KglAndroid : Kgl {
 
     override fun getAttribLocation(programId: Program, name: String) = GL.glGetAttribLocation(programId, name)
     override fun bindAttribLocation(programId: Program, index: Int, name: String) = GL.glBindAttribLocation(programId, index, name)
+
+    override fun createBuffer(): GlBuffer {
+        val buffers = IntArray(1)
+        GL.glGenBuffers(1, buffers, 0)
+        return buffers[0]
+    }
+
     override fun createBuffers(count: Int): Array<GlBuffer> {
         val buffers = IntArray(count)
         GL.glGenBuffers(count, buffers, 0)
@@ -99,6 +106,12 @@ class KglAndroid : Kgl {
 
     override fun clearColor(r: Float, g: Float, b: Float, a: Float) = GL.glClearColor(r, g, b, a)
 
+    override fun createTexture(): Texture {
+        val ints = IntArray(1)
+        GL.glGenTextures(1, ints, 0)
+        return ints[0]
+    }
+
     override fun createTextures(n: Int) : Array<Texture> {
         val ints = IntArray(n)
         GL.glGenTextures(n, ints, 0)
@@ -139,7 +152,7 @@ class KglAndroid : Kgl {
     override fun finish() = GL.glFinish()
 
     override fun bindFramebuffer(target: Int, framebuffer: Framebuffer?) = GL.glBindFramebuffer(target, framebuffer ?: 0)
-    override fun createFramebuffer(): Framebuffer? {
+    override fun createFramebuffer(): Framebuffer {
         val ints = IntArray(1)
         GL.glGenFramebuffers(1, ints, 0)
         return ints[0]
@@ -150,7 +163,7 @@ class KglAndroid : Kgl {
     override fun isFramebuffer(framebuffer: Framebuffer): Boolean = GL.glIsFramebuffer(framebuffer)
 
     override fun bindRenderbuffer(target: Int, renderbuffer: Renderbuffer?) = GL.glBindRenderbuffer(target, renderbuffer ?: 0)
-    override fun createRenderbuffer(): Renderbuffer? {
+    override fun createRenderbuffer(): Renderbuffer {
         val ints = IntArray(1)
         GL.glGenRenderbuffers(1, ints, 0)
         return ints[0]

kgl-jogl/src/main/kotlin/com/danielgergely/kgl/KglJogl.kt

@@ -88,6 +88,12 @@ class KglJogl(@JvmField private val gl: GL) : Kgl {
     override fun enableVertexAttribArray(location: Int) = gl.glEnableVertexAttribArray(location)
     override fun disableVertexAttribArray(location: Int) = gl.glDisableVertexAttribArray(location)
 
+    override fun createBuffer(): GlBuffer {
+        val buffers = IntArray(1)
+        gl.glGenBuffers(1, buffers, 0)
+        return buffers[0]
+    }
+
     override fun createBuffers(count: Int): Array<GlBuffer> {
         val buffers = IntArray(count)
         gl.glGenBuffers(count, buffers, 0)
@@ -162,6 +168,12 @@ class KglJogl(@JvmField private val gl: GL) : Kgl {
 
     override fun clear(mask: Int) = gl.glClear(mask)
 
+    override fun createTexture(): Texture {
+        val buffer = IntBuffer.allocate(1)
+        gl.glGenTextures(1, buffer)
+        return buffer[0]
+    }
+
     override fun createTextures(n: Int): Array<Texture> {
         val buffer = IntBuffer.allocate(n)
         gl.glGenTextures(n, buffer)
@@ -205,7 +217,7 @@ class KglJogl(@JvmField private val gl: GL) : Kgl {
     override fun finish() = gl.glFinish()
 
     override fun bindFramebuffer(target: Int, framebuffer: Framebuffer?) = gl.glBindFramebuffer(target, framebuffer ?: 0)
-    override fun createFramebuffer(): Framebuffer? {
+    override fun createFramebuffer(): Framebuffer {
         val ints = IntArray(1)
         gl.glGenFramebuffers(1, ints, 0)
         return ints[0]
@@ -216,7 +228,7 @@ class KglJogl(@JvmField private val gl: GL) : Kgl {
     override fun isFramebuffer(framebuffer: Framebuffer): Boolean = gl.glIsFramebuffer(framebuffer)
 
     override fun bindRenderbuffer(target: Int, renderbuffer: Renderbuffer?) = gl.glBindRenderbuffer(target, renderbuffer ?: 0)
-    override fun createRenderbuffer(): Renderbuffer? {
+    override fun createRenderbuffer(): Renderbuffer {
         val ints = IntArray(1)
         gl.glGenRenderbuffers(1, ints, 0)
         return ints[0]

kgl-lwjgl/src/main/kotlin/com/danielgergely/kgl/KglLwjgl.kt

@@ -67,6 +67,12 @@ class KglLwjgl : Kgl {
         GL.glCompileShader(shaderId)
     }
 
+    override fun createBuffer(): GlBuffer {
+        val array = IntArray(1)
+        GL.glGenBuffers(array)
+        return array[0]
+    }
+
     override fun createBuffers(count: Int): Array<GlBuffer> {
         val array = IntArray(count)
         GL.glGenBuffers(array)
@@ -86,6 +92,12 @@ class KglLwjgl : Kgl {
         }
     }
 
+    override fun createTexture(): Texture {
+        val array = IntArray(1)
+        GL.glGenTextures(array)
+        return array[0]
+    }
+
     override fun createTextures(n: Int): Array<Texture> {
         val array = IntArray(n)
         GL.glGenTextures(array)
@@ -253,14 +265,14 @@ class KglLwjgl : Kgl {
     override fun deleteVertexArray(vertexArrayObject: VertexArrayObject) = GL.glDeleteVertexArrays(vertexArrayObject)
 
     override fun bindFramebuffer(target: Int, framebuffer: Framebuffer?) = GL.glBindFramebuffer(target, framebuffer ?: 0)
-    override fun createFramebuffer(): Framebuffer? = GL.glGenFramebuffers()
+    override fun createFramebuffer(): Framebuffer = GL.glGenFramebuffers()
     override fun deleteFramebuffer(framebuffer: Framebuffer) = GL.glDeleteFramebuffers(framebuffer)
     override fun checkFramebufferStatus(target: Int): Int = GL.glCheckFramebufferStatus(target)
     override fun framebufferTexture2D(target: Int, attachment: Int, textarget: Int, texture: Texture, level: Int) = GL.glFramebufferTexture2D(target, attachment, textarget, texture, level)
     override fun isFramebuffer(framebuffer: Framebuffer): Boolean = GL.glIsFramebuffer(framebuffer)
 
     override fun bindRenderbuffer(target: Int, renderbuffer: Renderbuffer?) = GL.glBindRenderbuffer(target, renderbuffer ?: 0)
-    override fun createRenderbuffer(): Renderbuffer? = GL.glGenRenderbuffers()
+    override fun createRenderbuffer(): Renderbuffer = GL.glGenRenderbuffers()
     override fun deleteRenderbuffer(renderbuffer: Renderbuffer) = GL.glDeleteRenderbuffers(renderbuffer)
     override fun framebufferRenderbuffer(target: Int, attachment: Int, renderbuffertarget: Int, renderbuffer: Renderbuffer) = GL.glFramebufferRenderbuffer(target, attachment, renderbuffertarget, renderbuffer)
     override fun isRenderbuffer(renderbuffer: Renderbuffer): Boolean = GL.glIsRenderbuffer(renderbuffer)

kgl/src/commonMain/kotlin/com/danielgergely/kgl/Kgl.kt

@@ -28,6 +28,7 @@ interface Kgl {
     fun enableVertexAttribArray(location: Int)
     fun disableVertexAttribArray(location: Int)
 
+    fun createBuffer(): GlBuffer
     fun createBuffers(count: Int): Array<GlBuffer>
     fun bindBuffer(target: Int, bufferId: GlBuffer?)
     fun bufferData(target: Int, sourceData: Buffer, size: Int, usage: Int)
@@ -59,6 +60,7 @@ interface Kgl {
     fun clearColor(r: Float, g: Float, b: Float, a: Float)
     fun clear(mask: Int)
 
+    fun createTexture(): Texture
     fun createTextures(n: Int) : Array<Texture>
     fun deleteTexture(texture: Texture)
     fun texImage2D(target: Int, level: Int, internalFormat: Int, border: Int, resource: TextureResource)
@@ -78,14 +80,14 @@ interface Kgl {
     fun finish()
 
     fun bindFramebuffer(target: Int, framebuffer: Framebuffer?)
-    fun createFramebuffer(): Framebuffer?
+    fun createFramebuffer(): Framebuffer
     fun deleteFramebuffer(framebuffer: Framebuffer)
     fun checkFramebufferStatus(target: Int): Int
     fun framebufferTexture2D(target: Int, attachment: Int, textarget: Int, texture: Texture, level: Int)
     fun isFramebuffer(framebuffer: Framebuffer): Boolean
 
     fun bindRenderbuffer(target: Int, renderbuffer: Renderbuffer?)
-    fun createRenderbuffer(): Renderbuffer?
+    fun createRenderbuffer(): Renderbuffer
     fun deleteRenderbuffer(renderbuffer: Renderbuffer)
     fun framebufferRenderbuffer(target: Int, attachment: Int, renderbuffertarget: Int, renderbuffer: Renderbuffer)
     fun isRenderbuffer(renderbuffer: Renderbuffer): Boolean

kgl/src/jsMain/kotlin/com/danielgergely/kgl/Kgl.kt

@@ -46,6 +46,7 @@ class KglJs(private val gl: WebGLRenderingContext) : Kgl  {
     override fun enable(cap : Int) = gl.enable(cap)
     override fun disable(cap : Int) = gl.disable(cap)
 
+    override fun createBuffer(): GlBuffer = gl.createBuffer() ?: throw Exception()
     override fun createBuffers(count: Int): Array<GlBuffer> = Array(count) { gl.createBuffer() ?: throw Exception() }
 
     override fun bindBuffer(target: Int, bufferId: GlBuffer?) = gl.bindBuffer(target, bufferId.unsafeCast<WebGLBuffer>())
@@ -87,6 +88,7 @@ class KglJs(private val gl: WebGLRenderingContext) : Kgl  {
     override fun blendFunc(sFactor: Int, dFactor: Int) = gl.blendFunc(sFactor, dFactor)
     override fun cullFace(mode: Int) = gl.cullFace(mode)
 
+    override fun createTexture(): Texture = gl.createTexture() ?: throw Exception()
     override fun createTextures(n: Int): Array<Texture> = Array(n) { gl.createTexture() ?: throw Exception() }
     override fun deleteTexture(texture: Texture) = gl.deleteTexture(texture.unsafeCast<WebGLTexture>())
     override fun texImage2D(target: Int, level: Int, internalFormat: Int, border: Int, resource: TextureResource)
@@ -113,14 +115,14 @@ class KglJs(private val gl: WebGLRenderingContext) : Kgl  {
     override fun finish() = gl.finish()
 
     override fun bindFramebuffer(target: Int, framebuffer: Framebuffer?) = gl.bindFramebuffer(target, framebuffer.unsafeCast<WebGLFramebuffer>())
-    override fun createFramebuffer(): Framebuffer? = gl.createFramebuffer()
+    override fun createFramebuffer(): Framebuffer = gl.createFramebuffer() ?: throw Exception()
     override fun deleteFramebuffer(framebuffer: Framebuffer) = gl.deleteFramebuffer(framebuffer.unsafeCast<WebGLFramebuffer>())
     override fun checkFramebufferStatus(target: Int): Int = gl.checkFramebufferStatus(target)
     override fun framebufferTexture2D(target: Int, attachment: Int, textarget: Int, texture: Texture, level: Int) = gl.framebufferTexture2D(target, attachment, textarget, texture.unsafeCast<WebGLTexture>(), level)
     override fun isFramebuffer(framebuffer: Framebuffer): Boolean = gl.isFramebuffer(framebuffer.unsafeCast<WebGLFramebuffer>())
 
     override fun bindRenderbuffer(target: Int, renderbuffer: Renderbuffer?) = gl.bindRenderbuffer(target, renderbuffer.unsafeCast<WebGLRenderbuffer>())
-    override fun createRenderbuffer(): Renderbuffer? = gl.createRenderbuffer()
+    override fun createRenderbuffer(): Renderbuffer = gl.createRenderbuffer() ?: throw Exception()
     override fun deleteRenderbuffer(renderbuffer: Renderbuffer) = gl.deleteRenderbuffer(renderbuffer.unsafeCast<WebGLRenderbuffer>())
     override fun framebufferRenderbuffer(target: Int, attachment: Int, renderbuffertarget: Int, renderbuffer: Renderbuffer) = gl.framebufferRenderbuffer(target, attachment, renderbuffertarget, renderbuffer.unsafeCast<WebGLRenderbuffer>())
     override fun isRenderbuffer(renderbuffer: Renderbuffer): Boolean = gl.isRenderbuffer(renderbuffer.unsafeCast<WebGLRenderbuffer>())