# -*- coding: utf-8 -*- # Copyright (c) Vispy Development Team. All Rights Reserved. # Distributed under the (new) BSD License. See LICENSE.txt for more info. from __future__ import division from .linear import STTransform, NullTransform from .chain import ChainTransform from ._util import TransformCache from ...util.event import EventEmitter import numpy as np class TransformSystem(object): """ TransformSystem encapsulates information about the coordinate systems needed to draw a Visual. Visual rendering operates in six coordinate systems: * **Visual** - arbitrary local coordinate frame of the visual. Vertex buffers used by the visual are usually specified in this coordinate system. * **Scene** - This is an isometric coordinate system used mainly for lighting calculations. * **Document** - This coordinate system has units of _logical_ pixels, and should usually represent the pixel coordinates of the canvas being drawn to. Visuals use this coordinate system to make measurements for font size, line width, and in general anything that is specified in physical units (px, pt, mm, in, etc.). In most circumstances, this is exactly the same as the canvas coordinate system. * **Canvas** - This coordinate system represents the logical pixel coordinates of the canvas. It has its origin in the top-left corner of the canvas, and is typically the coordinate system that mouse and touch events are reported in. Note that, by convention, _logical_ pixels are not necessarily the same size as the _physical_ pixels in the framebuffer that is being rendered to. * **Framebuffer** - The buffer coordinate system has units of _physical_ pixels, and should usually represent the coordinates of the current framebuffer (on the canvas or an FBO) being rendered to. Visuals use this coordinate system primarily for antialiasing calculations. It is also the coorinate system used by glFragCoord. In most cases, this will have the same scale as the document and canvas coordinate systems because the active framebuffer is the back buffer of the canvas, and the canvas will have _logical_ and _physical_ pixels of the same size. However, the scale may be different in the case of high-resolution displays, or when rendering to an off-screen framebuffer with different scaling or boundaries than the canvas. * **Render** - This coordinate system is the obligatory system for vertices returned by a vertex shader. It has coordinates (-1, -1) to (1, 1) across the current glViewport. In OpenGL terminology, this is called clip coordinates. Parameters ---------- canvas : Canvas The canvas being drawn to. dpi : float The dot-per-inch resolution of the document coordinate system. By default this is set to the resolution of the canvas. Notes ----- By default, TransformSystems are configured such that the document coordinate system matches the logical pixels of the canvas, Examples -------- 1. To convert local vertex coordinates to normalized device coordinates in the vertex shader, we first need a vertex shader that supports configurable transformations:: vec4 a_position; void main() { gl_Position = $transform(a_position); } Next, we supply the complete chain of transforms when drawing the visual: def draw(tr_sys): tr = tr_sys.get_full_transform() self.program['transform'] = tr.shader_map() self.program['a_position'] = self.vertex_buffer self.program.draw('triangles') 2. Draw a line whose width is given in mm. To start, we need normal vectors for each vertex, which tell us the direction the vertex should move in order to set the line width:: vec4 a_position; vec4 a_normal; float u_line_width; float u_dpi; void main() { // map vertex position and normal vector to the document cs vec4 doc_pos = $visual_to_doc(a_position); vec4 doc_normal = $visual_to_doc(a_position + a_normal) - doc_pos; // Use DPI to convert mm line width to logical pixels float px_width = (u_line_width / 25.4) * dpi; // expand by line width doc_pos += normalize(doc_normal) * px_width; // finally, map the remainder of the way to normalized device // coordinates. gl_Position = $doc_to_render(a_position); } In this case, we need to access the transforms independently, so ``get_full_transform()`` is not useful here:: def draw(tr_sys): # Send two parts of the full transform separately self.program['visual_to_doc'] = tr_sys.visual_to_doc.shader_map() doc_to_render = (tr_sys.framebuffer_transform * tr_sys.document_transform) self.program['visual_to_doc'] = doc_to_render.shader_map() self.program['u_line_width'] = self.line_width self.program['u_dpi'] = tr_sys.dpi self.program['a_position'] = self.vertex_buffer self.program['a_normal'] = self.normal_buffer self.program.draw('triangles') 3. Draw a triangle with antialiasing at the edge. 4. Using inverse transforms in the fragment shader """ def __init__(self, canvas=None, dpi=None): self.changed = EventEmitter(source=self, type='transform_changed') self._canvas = None self._fbo_bounds = None self.canvas = canvas self._cache = TransformCache() self._dpi = dpi self._mappings = {'ct0': None, 'ct1': None, 'ft0': None} # Assign a ChainTransform for each step. This allows us to always # return the same transform objects regardless of how the user # configures the system. self._visual_transform = ChainTransform([NullTransform()]) self._scene_transform = ChainTransform([NullTransform()]) self._document_transform = ChainTransform([NullTransform()]) self._canvas_transform = ChainTransform([STTransform(), STTransform()]) self._framebuffer_transform = ChainTransform([STTransform()]) for tr in (self._visual_transform, self._scene_transform, self._document_transform, self._canvas_transform, self._framebuffer_transform): tr.changed.connect(self.changed) def _update_if_maps_changed(self, transform, map_key, new_maps): """Helper to store and check current (from, to) maps against new ones being provided. The new mappings are only applied if a change has occurred (and also stored in the current mappings). """ if self._mappings[map_key] is None: self._mappings[map_key] = new_maps transform.set_mapping(new_maps[0], new_maps[1]) else: if np.any(self._mappings[map_key] != new_maps): self._mappings[map_key] = new_maps transform.set_mapping(new_maps[0], new_maps[1]) def configure(self, viewport=None, fbo_size=None, fbo_rect=None, canvas=None): """Automatically configure the TransformSystem: * canvas_transform maps from the Canvas logical pixel coordinate system to the framebuffer coordinate system, taking into account the logical/physical pixel scale factor, current FBO position, and y-axis inversion. * framebuffer_transform maps from the current GL viewport on the framebuffer coordinate system to clip coordinates (-1 to 1). Parameters ========== viewport : tuple or None The GL viewport rectangle (x, y, w, h). If None, then it is assumed to cover the entire canvas. fbo_size : tuple or None The size of the active FBO. If None, then it is assumed to have the same size as the canvas's framebuffer. fbo_rect : tuple or None The position and size (x, y, w, h) of the FBO in the coordinate system of the canvas's framebuffer. If None, then the bounds are assumed to cover the entire active framebuffer. canvas : Canvas instance Optionally set the canvas for this TransformSystem. See the `canvas` property. """ # TODO: check that d2f and f2r transforms still contain a single # STTransform (if the user has modified these, then auto-config should # either fail or replace the transforms) if canvas is not None: self.canvas = canvas canvas = self._canvas if canvas is None: raise RuntimeError("No canvas assigned to this TransformSystem.") # By default, this should invert the y axis--canvas origin is in top # left, whereas framebuffer origin is in bottom left. map_from = [(0, 0), canvas.size] map_to = [(0, canvas.physical_size[1]), (canvas.physical_size[0], 0)] self._update_if_maps_changed(self._canvas_transform.transforms[1], 'ct1', np.array((map_from, map_to))) if fbo_rect is None: self._canvas_transform.transforms[0].scale = (1, 1, 1) self._canvas_transform.transforms[0].translate = (0, 0, 0) else: # Map into FBO coordinates map_from = [(fbo_rect[0], fbo_rect[1]), (fbo_rect[0] + fbo_rect[2], fbo_rect[1] + fbo_rect[3])] map_to = [(0, 0), fbo_size] self._update_if_maps_changed(self._canvas_transform.transforms[0], 'ct0', np.array((map_from, map_to))) if viewport is None: if fbo_size is None: # viewport covers entire canvas map_from = [(0, 0), canvas.physical_size] else: # viewport covers entire FBO map_from = [(0, 0), fbo_size] else: map_from = [viewport[:2], (viewport[0] + viewport[2], viewport[1] + viewport[3])] map_to = [(-1, -1), (1, 1)] self._update_if_maps_changed(self._framebuffer_transform.transforms[0], 'ft0', np.array((map_from, map_to))) @property def canvas(self): """ The Canvas being drawn to. """ return self._canvas @canvas.setter def canvas(self, canvas): self._canvas = canvas @property def dpi(self): """ Physical resolution of the document coordinate system (dots per inch). """ if self._dpi is None: if self._canvas is None: return None else: return self.canvas.dpi else: return self._dpi @dpi.setter def dpi(self, dpi): assert dpi > 0 self._dpi = dpi @property def visual_transform(self): """ Transform mapping from visual local coordinate frame to scene coordinate frame. """ return self._visual_transform @visual_transform.setter def visual_transform(self, tr): self._visual_transform.transforms = tr @property def scene_transform(self): """ Transform mapping from scene coordinate frame to document coordinate frame. """ return self._scene_transform @scene_transform.setter def scene_transform(self, tr): self._scene_transform.transforms = tr @property def document_transform(self): """ Transform mapping from document coordinate frame to the framebuffer (physical pixel) coordinate frame. """ return self._document_transform @document_transform.setter def document_transform(self, tr): self._document_transform.transforms = tr @property def canvas_transform(self): """ Transform mapping from canvas coordinate frame to framebuffer coordinate frame. """ return self._canvas_transform @canvas_transform.setter def canvas_transform(self, tr): self._canvas_transform.transforms = tr @property def framebuffer_transform(self): """ Transform mapping from pixel coordinate frame to rendering coordinate frame. """ return self._framebuffer_transform @framebuffer_transform.setter def framebuffer_transform(self, tr): self._framebuffer_transform.transforms = tr def get_transform(self, map_from='visual', map_to='render'): """Return a transform mapping between any two coordinate systems. Parameters ---------- map_from : str The starting coordinate system to map from. Must be one of: visual, scene, document, canvas, framebuffer, or render. map_to : str The ending coordinate system to map to. Must be one of: visual, scene, document, canvas, framebuffer, or render. """ tr = ['visual', 'scene', 'document', 'canvas', 'framebuffer', 'render'] ifrom = tr.index(map_from) ito = tr.index(map_to) if ifrom < ito: trs = [getattr(self, '_' + t + '_transform') for t in tr[ifrom:ito]][::-1] else: trs = [getattr(self, '_' + t + '_transform').inverse for t in tr[ito:ifrom]] return self._cache.get(trs) @property def pixel_scale(self): tr = self._canvas_transform return (tr.map((1, 0)) - tr.map((0, 0)))[0]