Adding modding folder with a hacked build.

modding/hacked/ui/opengl/VertexArrayObject.go

@@ -0,0 +1,62 @@
+package opengl
+
+// AttributeSetter is a callback function for a VertexArrayObject.
+type AttributeSetter func(OpenGL)
+
+// VertexArrayObject registers common vertex properties which are pre-set
+// before regular rendering loops.
+// Depending on the supported level of the Open GL API, these settings are
+// either buffered (using a VAO - vertex array object), or replayed for
+// every render call.
+type VertexArrayObject struct {
+	gl      OpenGL
+	program uint32
+	handle  uint32
+	setter  AttributeSetter
+}
+
+// NewVertexArrayObject returns a new instance.
+func NewVertexArrayObject(gl OpenGL, program uint32) *VertexArrayObject {
+	vao := &VertexArrayObject{
+		gl:      gl,
+		program: program,
+		handle:  gl.GenVertexArrays(1)[0],
+		setter:  func(OpenGL) {}}
+
+	return vao
+}
+
+// Dispose drops any associated resources.
+func (vao *VertexArrayObject) Dispose() {
+	vao.gl.DeleteVertexArrays([]uint32{vao.handle})
+	vao.handle = 0
+}
+
+// WithSetter registers the setter function for this object.
+// Depending on the support of the OpenGL API, this setter may be called
+// once immediately, or for each render call.
+func (vao *VertexArrayObject) WithSetter(setter AttributeSetter) {
+	if vao.handle != 0 {
+		vao.OnShader(func() { setter(vao.gl) })
+	}
+	vao.setter = setter
+}
+
+// OnShader executes the provided task with an activated shader program
+// and the vertex array object initialized.
+func (vao *VertexArrayObject) OnShader(task func()) {
+	gl := vao.gl
+
+	gl.UseProgram(vao.program)
+	gl.BindVertexArray(vao.handle)
+
+	defer func() {
+		gl.BindVertexArray(0)
+		gl.UseProgram(0)
+	}()
+
+	if vao.handle == 0 {
+		vao.setter(gl)
+	}
+	task()
+}