OpenGL Texture not displaying on iOS with Swift - ios

Question

I would like to show a texture with OpenGLES2 on iOS using Swift, but unfortunately the texture does not show up :-(. I don't know what I am doing wrong. Obviously the 'Test-Texture' is correctly loaded (and is POT). Maybe the call to glEnableVertexAttribArray is wrong?
func BUFFER_OFFSET(i: Int) -> UnsafePointer<Void> {
let p: UnsafePointer<Void> = nil
return p.advancedBy(i)
}
let vertices:[GLfloat] = [
// Positions // Colors // Texture Coords
0.5, 0.5, 0.0, 1.0, 0.0, 0.0, 1.0, 1.0, // Top Right
0.5, -0.5, 0.0, 0.0, 1.0, 0.0, 1.0, 0.0, // Bottom Right
-0.5, -0.5, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, // Bottom Left
-0.5, 0.5, 0.0, 1.0, 1.0, 0.0, 0.0, 1.0 // Top Left
]
let indices:[GLuint] = [ // Note that we start from 0!
0, 1, 3, // First Triangle
1, 2, 3 // Second Triangle
]
func setupGL() {
EAGLContext.setCurrentContext(self.context)
self.loadShaders()
self.effect = GLKBaseEffect()
self.effect!.light0.enabled = GLboolean(GL_TRUE)
self.effect!.light0.diffuseColor = GLKVector4Make(1.0, 0.4, 0.4, 1.0)
do {
testTexture = try GLKTextureLoader.textureWithContentsOfFile(NSBundle.mainBundle().pathForResource("MyTexture1024x1024", ofType: "png")!, options: [GLKTextureLoaderOriginBottomLeft:true, GLKTextureLoaderApplyPremultiplication:true])
print("successfully loaded test texture")
}
catch let error as NSError {
print("could not load test texture \(error)")
}
glEnable(GLenum(GL_DEPTH_TEST))
glGenVertexArraysOES(1, &vertexArray)
glBindVertexArrayOES(vertexArray)
glGenBuffers(1, &vertexBuffer)
glBindBuffer(GLenum(GL_ARRAY_BUFFER), vertexBuffer)
glBufferData(GLenum(GL_ARRAY_BUFFER), GLsizeiptr(sizeof(GLfloat) * vertices.count), vertices, GLenum(GL_STATIC_DRAW))
glGenBuffers(1, &indexBuffer)
glBindBuffer(GLenum(GL_ELEMENT_ARRAY_BUFFER), indexBuffer)
glBufferData(GLenum(GL_ELEMENT_ARRAY_BUFFER), GLsizeiptr(sizeof(GLfloat) * indices.count), indices, GLenum(GL_STATIC_DRAW))
glEnableVertexAttribArray(GLuint(GLKVertexAttrib.Position.rawValue))
glVertexAttribPointer(GLuint(GLKVertexAttrib.Position.rawValue), 3, GLenum(GL_FLOAT), GLboolean(GL_FALSE), GLsizei(sizeof(GLfloat) * 8), BUFFER_OFFSET(0))
glEnableVertexAttribArray(GLuint(GLKVertexAttrib.TexCoord0.rawValue))
glVertexAttribPointer(GLuint(GLKVertexAttrib.TexCoord0.rawValue), 2, GLenum(GL_FLOAT), GLboolean(GL_FALSE), GLsizei(sizeof(GLfloat) * 8), BUFFER_OFFSET(sizeof(GLfloat) * 6))
glBindVertexArrayOES(0)
}
override func glkView(view: GLKView, drawInRect rect: CGRect) {
glClearColor(0.65, 0.65, 0.65, 1.0)
glClear(GLbitfield(GL_COLOR_BUFFER_BIT) | GLbitfield(GL_DEPTH_BUFFER_BIT))
//use specified vertex buffer
glBindVertexArrayOES(vertexArray)
//use specified index buffer
glBindBuffer(GLenum(GL_ELEMENT_ARRAY_BUFFER), indexBuffer)
glEnable(GLenum(GL_BLEND));
glBlendFunc(GLenum(GL_SRC_ALPHA), GLenum(GL_ONE_MINUS_SRC_ALPHA));
self.effect!.texture2d0.name = testTexture.name
self.effect!.texture2d0.enabled = 1
// Render the object with GLKit
self.effect!.prepareToDraw()
glDrawElements(GLenum(GL_TRIANGLES), 6, GLenum(GL_UNSIGNED_INT), nil)
}

Answer 1

Finally, I found the cause of the problem, which was the following code that is not included above (in setupGL()):
self.effect = GLKBaseEffect()
self.effect!.light0.enabled = GLboolean(GL_TRUE)
self.effect!.light0.diffuseColor = GLKVector4Make(1.0, 0.4, 0.4, 1.0)
So the reason was actually the light. When disabled it works!
self.effect = GLKBaseEffect()
self.effect!.light0.enabled = GLboolean(GL_FALSE)