Method Update

common/render.go:333–407

Update draws the entities in the RenderSystem to the OpenGL Surface.

(dt float32)

// Update draws the entities in the RenderSystem to the OpenGL Surface.
func (rs *RenderSystem) Update(dt float32) {
	if engo.Headless() {
		return
	}

	if rs.sortingNeeded {
		sort.Sort(rs.entities)
		rs.sortingNeeded = false
	}

	if rs.newCamera {
		newCamera(rs.world)
		rs.newCamera = false
	}

	engo.Gl.Clear(engo.Gl.COLOR_BUFFER_BIT)

	preparedCullingShaders := make(map[CullingShader]struct{})
	var cullingShader CullingShader // current culling shader
	var prevShader Shader           // shader of the previous entity
	var currentShader Shader        // currently "active" shader

	// TODO: it's linear for now, but that might very well be a bad idea
	for _, e := range rs.entities {
		if e.RenderComponent.Hidden {
			continue // with other entities
		}

		// Retrieve a shader, may be the default one -- then use it if we aren't already using it
		shader := e.RenderComponent.shader

		if !compareShaders(shader, prevShader) {
			// to increase performance avoid the type assertions when possible
			prevShader = shader
			if cs, ok := shader.(CullingShader); ok {
				cullingShader = cs
				if _, isPrepared := preparedCullingShaders[cullingShader]; !isPrepared {
					cullingShader.PrepareCulling()
					preparedCullingShaders[cullingShader] = struct{}{}
				}
			} else {
				cullingShader = nil
			}
		}

		if cullingShader != nil && !cullingShader.ShouldDraw(e.RenderComponent, e.SpaceComponent) {
			continue
		}

		// Change Shader if we have to
		if !compareShaders(shader, currentShader) {
			if currentShader != nil {
				currentShader.Post()
			}
			shader.Pre()
			currentShader = shader
		}