// drawLoop is the primary drawing loop.
//
// After Cocoa has created an NSWindow and called prepareOpenGL,
// it starts drawLoop on a locked goroutine to handle OpenGL calls.
//
// The screen is drawn every time a paint.Event is received, which can be
// triggered either by the user or by Cocoa via drawgl (for example, when
// the window is resized).
func drawLoop(w *windowImpl, vba uintptr) {
runtime.LockOSThread()
C.makeCurrentContext(C.uintptr_t(w.ctx))
// Starting in OS X 10.11 (El Capitan), the vertex array is
// occasionally getting unbound when the context changes threads.
//
// Avoid this by binding it again.
C.glBindVertexArray(C.GLuint(vba))
if errno := C.glGetError(); errno != 0 {
panic(fmt.Sprintf("gldriver: glBindVertexArray failed: %d", errno))
}
workAvailable := w.worker.WorkAvailable()
// TODO(crawshaw): exit this goroutine on Release.
for {
select {
case <-workAvailable:
w.worker.DoWork()
case <-w.publish:
loop:
for {
select {
case <-workAvailable:
w.worker.DoWork()
default:
break loop
}
}
C.flushContext(C.uintptr_t(w.ctx))
w.publishDone <- screen.PublishResult{}
}
}
}
func initGL() {
// Using attribute arrays in OpenGL 3.3 requires the use of a VBA.
// But VBAs don't exist in ES 2. So we bind a default one.
var id C.GLuint
C.glGenVertexArrays(1, &id)
C.glBindVertexArray(id)
}
// createContext creates an OpenGL context, binds it as the current context
// stored in thread-local storage, and locks the current goroutine to an os
// thread.
func createContext() *contextGL {
// The OpenGL active context is stored in TLS.
runtime.LockOSThread()
c := new(contextGL)
C.CGCreate(&c.ctx)
// Using attribute arrays in OpenGL 3.3 requires the use of a VBA.
// But VBAs don't exist in ES 2. So we bind a default one.
var id C.GLuint
C.glGenVertexArrays(1, &id)
C.glBindVertexArray(id)
return c
}
// createContext creates an OpenGL context, binds it as the current context
// stored in thread-local storage, and locks the current goroutine to an os
// thread.
func createContext() (*contextGL, error) {
// The OpenGL active context is stored in TLS.
runtime.LockOSThread()
c := new(contextGL)
if cglErr := C.CGCreate(&c.ctx); cglErr != C.kCGLNoError {
return nil, fmt.Errorf("CGL: %v", C.GoString(C.CGLErrorString(cglErr)))
}
// Using attribute arrays in OpenGL 3.3 requires the use of a VBA.
// But VBAs don't exist in ES 2. So we bind a default one.
var id C.GLuint
C.glGenVertexArrays(1, &id)
C.glBindVertexArray(id)
return c, nil
}
func BindVertexArray(array VertexArray) {
C.glBindVertexArray(C.GLuint(array))
}
func (array VertexArray) Bind() {
C.glBindVertexArray(C.GLuint(array))
}
func (array VertexArray) Unbind() {
C.glBindVertexArray(C.GLuint(0))
}