Content from app import App from array import array from buttons import _num from math import radians, tan from micropython import const from tidal import * from tidal3d import * import time from .buffdisp import BufferedDisplay from .object import Mesh MODE_POINT_CLOUD = const(0) MODE_WIREFRAME_FULL = const(1) MODE_WIREFRAME_BACK_FACE_CULLING = const(2) MODE_SOLID = const(3) MODE_SOLID_SHADED = const(4) class Renderer(App): def __init__(self): super().__init__() # We'll render the scene to an off-screen buffer and blit it to the display # all at once when we're ready self.fb = BufferedDisplay(display) # Initial render mode and object, see the constants above for other modes self.render_mode = MODE_SOLID_SHADED self.render_object = 'cube.obj' # Projection matrix self.m_proj = Renderer.perspective_matrix(90, self.fb.width / self.fb.height, 0.1, 100) # Camera position and view transformation matrix # TODO a proper camera system self.v_campos = array('f', [0, 10, 35]) self.m_view = Renderer.identity_matrix() m_translate(self.m_view, array('f', [0, -10, -35])) # Lighting vector self.v_light = array('f', [-1, -1, -2]) v_normalise(self.v_light) # Model to render self.mesh = Mesh(self.render_object) self.start_t = 0 self.accum_t = 0 self.frame_counter = 0 self.fps = 0 @staticmethod def identity_matrix(): """ Returns the identity matrix, multiplication of any matrix M with the identity matrix will yield the original matrix M """ return array('f', [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]) @staticmethod def perspective_matrix(fov, aspect, near, far): """ Returns the perspective projection matrix for the given field of view and aspect ratio, multiplication of any vector V with the projection matrix will yield normalised device coordinates """ proj_mat = [0] * 16 # Set the field of view, accomodating for the aspect ratio of the screen scale = tan(radians(fov * 0.5)) proj_mat[0] = 1.0 / (scale * aspect) # Scale of the x coord of the projected vertex proj_mat[5] = 1.0 / scale # Scale of the y coord of the projected vertex # Z clipping planes proj_mat[10] = -far / (far - near) proj_mat[14] = -far * near / (far - near) # Setting these following values is how we do the perspective division, by causing w to be set to -z # instead of 1 and then w is used as the normalising divisor during vector-proj_mat multiplication proj_mat[11] = -1 proj_mat[15] = 0 return array('f', proj_mat) def on_activate(self): super().on_activate() # Register input callbacks self.buttons.on_press(BUTTON_A, self.select_mode) self.buttons.on_press(BUTTON_B, self.select_object) self.buttons.on_press(JOY_UP, self.button_up, False) self.buttons.on_press(JOY_DOWN, self.button_down, False) self.buttons.on_press(JOY_LEFT, self.button_left, False) self.buttons.on_press(JOY_RIGHT, self.button_right, False) self.start_t = time.ticks_us() self.loop() def on_deactivate(self): self.timer.cancel() super().on_deactivate() def select_mode(self): # Cycle through the render modes self.render_mode += 1 if self.render_mode > MODE_SOLID_SHADED: self.render_mode = 0 def select_object(self): # Cycle through objects to render if self.render_object == 'cube.obj': self.render_object = 'teapot.obj' elif self.render_object == 'teapot.obj': self.render_object = 'cube.obj' # Reload the model self.mesh = Mesh(self.render_object) def button_left(self): self.mesh.rotate_y(45) def button_right(self): self.mesh.rotate_y(-45) def button_up(self): self.mesh.rotate_x(45) def button_down(self): self.mesh.rotate_x(-45) def _get_button_state(self, pin): # Buttons are active so invert to make truthy mean pressed, which seems more intuitive return not self.buttons._callbacks[_num(pin)].state def loop(self): last_t = self.start_t self.start_t = time.ticks_us() delta_t = time.ticks_diff(self.start_t, last_t) # Update the simulation self.update(delta_t / 1000000) # Render the scene self.render_background() self.render_scene(self.render_mode) self.render_foreground() self.fb.blit() # Calculate frames per second self.frame_counter += 1 self.accum_t += delta_t if self.accum_t > 1000000: self.accum_t -= 1000000 self.fps = self.frame_counter self.frame_counter = 0 # Show the time it took to render the frame print("{:,} us".format(delta_t)) self.timer = self.after(1, self.loop) def update(self, delta_t): # Kill velocity if buttons no longer pressed if not self._get_button_state(JOY_LEFT) and not self._get_button_state(JOY_RIGHT): self.mesh.rotate_y(0) if not self._get_button_state(JOY_UP) and not self._get_button_state(JOY_DOWN): self.mesh.rotate_x(0) self.mesh.update(delta_t) def render_background(self): fb = self.fb # Just clear the framebuffer by filling it with a solid colour fb.rect(0, 0, fb.width, fb.height, BLACK, True) # Show some instructions on screen fb.text("A = RENDER MODE", 0, 0, WHITE) fb.text("B = NEXT OBJECT", 0, 10, WHITE) fb.text("JOY = ROTATE", 0, 20, WHITE) def render_scene(self, render_mode): fb = self.fb # Cached references to frequently accessed mesh properties mesh = self.mesh faces = mesh.faces verts = mesh.vertices_trans norms = mesh.normals_trans depth_map = mesh.depth_map # Transform all vertices to their positions in the world by multiplying by the model # transformation matrix, which is specific to the mesh being rendered (create world # coordinates) # Note that translating doesn't mean anything for vectors, so normals are rotated only, # and vertices are both rotated and translated m_model = Renderer.identity_matrix() m_rotate(m_model, mesh.orientation) v_multiply_batch(mesh.normals, m_model, norms) m_translate(m_model, mesh.position) v_multiply_batch(mesh.vertices, m_model, verts) # Pre-allocated space for intermediate calculations to minimise object instantiations, # which really helps with performance sensitive applications like this camera = array('f', [0, 0, 0]) centre = array('f', [0, 0, 0]) rgb = array('f', [0, 0, 0]) coords = array('h', [0] * 6) face_verts = [None, None, None] # Generate a list of faces for rendering num_faces = 0 for face_index in range(len(faces)): indices, norm_index, _ = faces[face_index] # Calculate the point in the centre of the face face_verts[0] = verts[indices[0]] face_verts[1] = verts[indices[1]] face_verts[2] = verts[indices[2]] v_average(face_verts, centre) # Calculate the the direction to the camera from the centre of the face v_subtract(self.v_campos, centre, camera) v_normalise(camera) # Now we use the dot product to determine if the front of the face is pointing at the # camera; if the angle between the normal vector and the camera vector is greater than # 90 degrees then we are seeing the back of the face, and if we are culling back faces # then we can avoid rendering it dot = v_dot(norms[norm_index], camera) if (dot < 0 and render_mode >= MODE_WIREFRAME_BACK_FACE_CULLING): continue # Record the face for rendering along with its average depth from the camera, the face's # depth is the z component of the centre point transformed by the camera view matrix v_multiply(centre, self.m_view) depth_map[num_faces * 2] = face_index depth_map[num_faces * 2 + 1] = centre[2] num_faces += 1 # A painter's algorithm; use the face's average depth value to order them from back to front, # this ensures far away faces are not drawn on top of near faces z_sort(depth_map, num_faces) # Since faces can share vertices, and matrix multiplication is expensive, let's not project # a vertex more than once, we'll just keep a list of vertices that we've already projected projected_verts = [False] * len(mesh.vertices) # Render faces m_view = self.m_view m_proj = self.m_proj for i in range(0, num_faces * 2, 2): face_index = int(depth_map[i]) indices, norm_index, col_index = faces[face_index] visible = False # Let's go ahead and project the face's vertices for j in range(3): index = indices[j] vertex = verts[index] # Only project a vertex if we've not already done so if not projected_verts[index]: projected_verts[index] = True # Transform the world coorinates into camera coordinates by multiplying by the # camera view matrix, allowing it be viewed from the camera's point of view v_multiply(vertex, m_view) # Project the vertex onto a 2D plane by multiplying by the projection matrix, this # yields normalised device coords where all points that lie within the viewable # space defined by the field of view are mapped to between -1.0, 1.0 # The projection matrix multiplication also performs the perspective division, # which makes more distant points appear further away by making them closer together # on the x and y axes v_multiply(vertex, m_proj) # If a face's projected vertices all lie outside the viewable space (x or y is more # than 1 or less then -1) then we can cull it because it will not be seen; if at least # one vertex can be seen, we'll render the partial face if vertex[0] > -1 and vertex[0] < 1 and vertex[1] > -1 and vertex[1] < 1: visible = True face_verts[j] = vertex # If none of this face's vertices can be seen, continue to the next face if not visible: continue # Convert normalised device coordinates (NDCs) to screen coordinates, if an NDC's x and y # components both lie between -1 and 1, it will result in a valid on-screen pixel location # This is implemented in native code for speed reasons, but it just does this: # x = (v[0] + 1) * 0.5 * width # y = (1 - (v[1] + 1) * 0.5) * height # Obviously the y axis here is inverted because screens tend to have the origin 0,0 at the # top left and increases towards the bottom v_ndc_to_screen(face_verts, coords, fb.width, fb.height) colour = WHITE if render_mode > MODE_POINT_CLOUD and render_mode < MODE_SOLID_SHADED: # Solid, unshaded colour v_scale(mesh.colours[col_index], 1, rgb) colour = color565(int(rgb[0]), int(rgb[1]), int(rgb[2])) elif render_mode >= MODE_SOLID_SHADED: # Scale the color by the angle of incidence of the light vector so a face appears # more brightly lit the closer to orthogonal it is, but clamp to a minimum value # so unlit faces are not totally invisible, simulating a bit of ambient light dot = v_dot(norms[norm_index], self.v_light) v_scale(mesh.colours[col_index], -dot, rgb) colour = color565(max(int(rgb[0]), 8), max(int(rgb[1]), 8), max(int(rgb[2]), 8)) # Draw to the framebuffer using screen coordinates if render_mode == MODE_POINT_CLOUD: fb.points(coords, colour) elif render_mode == MODE_WIREFRAME_FULL or render_mode == MODE_WIREFRAME_BACK_FACE_CULLING: fb.polygon(coords, colour) elif render_mode >= MODE_SOLID: fb.polygon(coords, colour, True) def render_foreground(self): self.fb.text("{0:2d} fps".format(self.fps), 0, self.fb.height - 10, WHITE) # Set the entrypoint for the app launcher main = Renderer