New tile based platform engine – part 11 – slopes part a

I decided to split slopes in two parts, because they are a bit more difficult than other tile types.

In this part, you can walk on slopes but you can’t jump on/from them. Oh, well, you can actually jump or land on them, but without the second part of the code, there could be some glitches.

Obviously if you want to suggest your jumping routine, you’re welcome.

Slopes need a lot of rules in order to work, that can be summarized in one big rule: don’t make senseless slopes.

For senseless slopes I mean everything… senseless… refer to the picture:

Green shapes show some possible slopes while red ones show impossible ones.

Then the `is_on_slope` function solves slope walking.

Once I’ll publish jumping routine, I’ll write a detailed slope tutorial.

Meanwhile take the source code:

```walkable_tiles = Array(0, 5, 6, 7, 10, 11);
tile_size = 20;
ground_acceleration = 1;
ground_friction = 0.8;
air_acceleration = 0.5;
air_friction = 0.7;
ice_acceleration = 0.15;
ice_friction = 0.95;
max_speed = 3;
xspeed = 0;
yspeed = 0;
falling = false;
on_slope = false;
gravity = 0.5;
jump_speed = 6;
climbing = false;
climb_speed = 0.8;
level = new Array();
enemy = new Array();
coin = new Array();
key = new Array();
level[0] = [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1];
level[1] = [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1];
level[2] = [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 1, 0, 0, 0, 0, 1];
level[3] = [1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 1];
level[4] = [1, 0, 1, 2, 2, 1, 0, 4, 4, 8, 3, 3, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 1];
level[5] = [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 6, 0, 0, 0, 0, 0, 1];
level[6] = [1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 1, 0, 0, 0, 0, 0, 1];
level[7] = [1, 1, 1, 0, 0, 1, 0, 0, 0, 10, 1, 11, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 1];
level[8] = [1, 1, 1, 1, 0, 9, 0, 0, 10, 1, 1, 1, 11, 0, 7, 0, 0, 6, 0, 0, 0, 0, 7, 0, 1];
level[9] = [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 1, 4, 4, 1, 8, 1, 8, 1];
player = [10, 6];
enemy[0] = [10, 3, -2];
enemy[1] = [3, 3, -2];
coin[0] = [2, 2];
coin[1] = [23, 4];
key[0] = [1, 5, 5, 8];
function create_level(l) {
_root.createEmptyMovieClip("level_container",1);
level_height = l.length;
level_width = l[0].length;
for (y=0; ymax_speed) {
xspeed = max_speed;
}
if (xspeed0 and !on_slope) {
if ((bottom_right != 0 and bottom_right != 6 and bottom_right != 10) or (bottom_left != 0 and bottom_left != 6 and bottom_left != 10)) {
// not a cloud...
if (bottom_right != 5 and bottom_left != 5) {
// a trampoline
if ((bottom_right == 7 or bottom_left == 7) and (Math.abs(yspeed)>1)) {
yspeed = yspeed*-1;
jumping = true;
falling = true;
}
else {
y_pos = bottom*tile_size-9;
yspeed = 0;
falling = false;
jumping = false;
}
}
else {
//cloud
if (prev_bottom0) {
if (!is_walkable(top_right) or !is_walkable(bottom_right)) {
x_pos = right*tile_size-6;
xspeed = 0;
}
}
prev_bottom = bottom;
}
function get_edges() {
// right edge
right = Math.floor((x_pos+5)/tile_size);
// left edge
left = Math.floor((x_pos-6)/tile_size);
// bottom edge
bottom = Math.floor((y_pos+8)/tile_size);
// top edge
top = Math.floor((y_pos-9)/tile_size);
top_right = level[top][right];
top_left = level[top][left];
bottom_left = level[bottom][left];
bottom_right = level[bottom][right];
}
function place_player() {
level_container.hero.removeMovieClip();
x_pos = player[0]*tile_size+tile_size/2;
y_pos = player[1]*tile_size+tile_size/2+1;
level_container.attachMovie("hero","hero",_root.level_container.getNextHighestDepth(),{_x:x_pos, _y:y_pos});
}
function is_walkable(tile) {
walkable = false;
if (!on_slope) {
for (x=0; x
And the final example:

```
215 GAME PROTOTYPES EXPLAINED WITH SOURCE CODE
// 1+2=3
// 10000000
// 2 Cars
// 2048
// Avoider
// Ballz
// Block it
// Blockage
// Bloons
// Boids
// Bombuzal
// Breakout
// Bricks
// Columns
// CubesOut
// Dots
// DROP'd
// Dudeski
// Eskiv
// Filler
// Fling
// Globe
// HookPod
// Hundreds
// InkTd
// Iromeku
// Lumines
// Magick
// MagOrMin
// Maze
// Memdot
// Nano War
// Nodes
// o:anquan
// Ononmin
// Pacco
// Phyballs
// Platform
// Poker
// Pool
// Poux
// Pudi
// qomp
// Racing
// Renju
// SameGame
// Security
// Sling
// Slingy
// Sokoban
// Splitter
// Sproing
// Stack
// Stairs
// Stringy
// Sudoku
// Tetris
// Threes
// Toony
// Turn
// TwinSpin
// vvvvvv
// Wordle
// Worms
// Yanga
// Zhed
// zNumbers