crystal.window.draw_via_canvas

Advanced

Draws on a canvas, and then draws the canvas onto the screen. The transformation stack is reset while drawing on the canvas, but internally preserved for the purpose of tracking areas that can be interacted with the mouse.

This function is used internally by crystal.window.draw_native and by Painter UI elements.

Usage

crystal.window.draw_via_canvas(canvas, draw_function, blit_function);

Arguments

Name	Type	Description
canvas	love.Canvas	Canvas to draw onto.
draw_function	function	Function containing logic to draw onto the canvas.
blit_function	function	Function containing logic to draw the canvas onto the screen.

Examples

This example defines a scene where a post-processing effect is applied to the entire screen using a canvas.

MyScene = Class("MyScene", crystal.Scene);

MyScene.init = function(self)
  self.canvas = love.graphics.newCanvas();
  self.post_process = crystal.assets.get("crt_effect.glsl");
end

MyScene.draw = function(self)
  crystal.window.draw_via_canvas(
    self.canvas,
    function()
      -- Draw the game
    end,
    function()
      love.graphics.push("all");
      love.graphics.setShader(self.post_process);
      love.graphics.draw(self.canvas);
      love.graphics.pop();
    end,
  );
end

An incorrect implementation of the draw function is presented below. In this version, mouse interactions would not get detected correctly:

MyScene.draw = function(self)

  -- INCORRECT CODE - DO NOT COPY

  love.graphics.push("all");
  love.graphics.setCanvas(self.canvas);
  love.graphics.reset();
  -- Draw the game
  love.graphics.pop();

  love.graphics.push("all");
  love.graphics.setShader(self.post_process);
  love.graphics.draw(self.canvas);
  love.graphics.pop();
end