doodle/pkg/collision/collide_level.go
Noah Petherbridge 94d0da78e7 Swimming Physics and Bubble Pattern
Water pixels finally do something other than turn your character blue!

* When the player character is "wet" (touching water pixels, and so appearing in
  a blue mask), water physics apply: gravity is slower, your jump height is
  halved, but you get infinite jumps to swim higher in the water.
* Holding the jump key under water will incur a short delay between jumps, so
  that you don't just fly straight up to the surface. Tap the jump button to
  move up quicker, you can spam it all you want.

Azulians are also able to handle being under water:

* They'll sink to the bottom and keep walking back and forth normally.
* If you are above them and noticed, they'll jump (swim) up towards you,
  aware of the water and it jumps like you do.
* The Blue Azulian has the poorest vertical aggro range so it isn't a
  very good swimmer. The White Azulian is very good at navigating water
  as it can pursue the player from the furthest distance of them all.

Changes to the editor:

* New brush pattern added: bubbles.png
  * It's the default pattern now for the "water" color of all
    of the built-in palettes instead of ink.png
  * A repeating pattern of bubbles carved out showing the
    level wallpaper.
  * The old "Bubbles (circles.png)" is renamed "Circles"
* The last scroll position is saved with the Level file, so when you reload
  the level later it's scrolled at where you left it.
2022-05-05 21:35:32 -07:00

323 lines
8.4 KiB
Go

package collision
import (
"sync"
"git.kirsle.net/apps/doodle/pkg/balance"
"git.kirsle.net/apps/doodle/pkg/level"
"git.kirsle.net/go/render"
)
// Collide describes how a collision occurred.
type Collide struct {
Top bool
TopPoint render.Point
TopPixel *level.Swatch
Left bool
LeftPoint render.Point
LeftPixel *level.Swatch
Right bool
RightPoint render.Point
RightPixel *level.Swatch
Bottom bool
BottomPoint render.Point
BottomPixel *level.Swatch
MoveTo render.Point
// Swatch attributes affecting the collision at this time.
InFire string // the name of the swatch, Fire = general ouchy color.
InWater bool
}
// Reset a Collide struct flipping all the bools off, but keeping MoveTo.
func (c *Collide) Reset() {
c.Top = false
c.Left = false
c.Right = false
c.Bottom = false
c.InWater = false
}
// Side of the collision box (top, bottom, left, right)
type Side uint8
// Options for the Side type.
const (
Top Side = iota
Bottom
Left
Right
)
/*
CollidesWithGrid checks if a Doodad collides with level geometry.
The `target` is the point the actor wants to move to on this tick.
*/
func CollidesWithGrid(d Actor, grid *level.Chunker, target render.Point) (*Collide, bool) {
var (
P = d.Position()
S = d.Size()
hitbox = d.Hitbox()
result = &Collide{
MoveTo: P,
}
ceiling bool // Has hit a ceiling?
capHeight int // Stop vertical movement thru a ceiling
capLeft int // Stop movement thru a wall
capRight int
capFloor int // Stop movement thru the floor
hitLeft bool // Has hit an obstacle on the left
hitRight bool // or right
hitFloor bool
)
// Adjust the actor's bounding rect by its stated Hitbox from its script.
// e.g.: Boy's Canvas size is 56x56 but he is a narrower character with a
// hitbox width smaller than its Canvas size.
S = SizePlusHitbox(GetBoundingRect(d), hitbox)
// Test if we are ALREADY colliding with level geometry and try and wiggle
// free. ScanBoundingBox scans level pixels along the four edges of the
// actor's hitbox in world space.
if ok := result.ScanBoundingBox(GetBoundingRectHitbox(d, hitbox), grid); ok {
// We've already collided! Try to wiggle free.
if result.Bottom {
if !d.Grounded() {
d.SetGrounded(true)
}
} else {
d.SetGrounded(false)
}
if result.Top {
ceiling = true
P.Y++
}
if result.Left {
P.X++
}
if result.Right {
P.X--
}
}
// If grounded, cap our Y position.
if d.Grounded() {
if !result.Bottom {
// We've fallen off a ledge.
d.SetGrounded(false)
} else if target.Y < P.Y {
// We're moving upward.
d.SetGrounded(false)
} else {
// Cap our downward motion to our current position,
// fighting the force of gravity.
target.Y = P.Y
}
}
// Cap our horizontal movement if we're touching walls.
if (result.Left && target.X < P.X) || (result.Right && target.X > P.X) {
// If the step is short enough, try and jump up.
height := P.Y + S.H
if result.Left { // && target.X < P.X {
height -= result.LeftPoint.Y
} else {
height -= result.RightPoint.Y
}
if height <= balance.SlopeMaxHeight {
target.Y -= height
if target.X < P.X {
target.X-- // push along to the left
} else if target.X > P.X {
target.X++ // push along to the right
}
} else {
target.X = P.X
}
}
// Cap our vertical movement if we're touching ceilings.
if ceiling {
// The existing box intersects a ceiling, this will almost never
// happen because gravity will always pull you away at the last frame.
// But if we do somehow get here, may as well cap it where it's at.
capHeight = P.Y
}
// Trace a line from where we are to where we wanna go.
result.Reset()
result.MoveTo = P
for point := range render.IterLine(P, target) {
// Before we compute their next move, if we're already capping their
// height make sure the new point stays capped too. This prevents them
// clipping thru a ceiling if they were also holding right/left too.
if capHeight != 0 && point.Y < capHeight {
point.Y = capHeight
}
if capLeft != 0 && point.X < capLeft {
// TODO: this along with a "+ 1" hack prevents clipping thru the
// left wall sometimes, but breaks walking up leftward slopes.
point.X = capLeft
}
if capRight != 0 && point.X > capRight {
// This if check fixes the climbing-walls-on-the-right bug.
point.X = capRight
}
if has := result.ScanBoundingBox(render.Rect{
X: point.X,
Y: point.Y,
W: S.W,
H: S.H,
}, grid); has {
if result.Bottom {
if !hitFloor {
hitFloor = true
capFloor = result.BottomPoint.Y - S.H
}
d.SetGrounded(true)
}
if result.Top && !ceiling {
// This is a newly discovered ceiling.
ceiling = true
capHeight = result.TopPoint.Y + 1
// TODO: the "+ 1" helps prevent clip thru ceiling, probably.
// Similar to the "+ 1" on the left side, below.
}
if result.Left && !hitLeft {
hitLeft = true
capLeft = result.LeftPoint.X // + 1
// TODO: there was a clipping bug where the player could clip
// thru a left wall if they jumped slightly while pressing into
// it. (90 degree angle between floor and left wall). The bug
// does NOT repro on right walls, only left. The "+ 1" added to
// capLeft works around it, BUT breaks walking up leftward slopes
// (walking up rightward slopes still works).
}
if result.Right && !hitRight {
hitRight = true
capRight = result.RightPoint.X - S.W
}
}
// So far so good, keep following the MoveTo to
// the last good point before a collision.
result.MoveTo = point
}
// If they hit the roof, cap them to the roof.
if ceiling && result.MoveTo.Y < capHeight {
result.Top = true
result.MoveTo.Y = capHeight
}
if hitFloor && result.MoveTo.Y > capFloor {
result.Bottom = true
result.MoveTo.Y = capFloor
}
if hitLeft {
result.Left = true
result.MoveTo.X = capLeft
}
if hitRight {
result.Right = true
result.MoveTo.X = capRight
}
return result, result.IsColliding()
}
// IsColliding returns whether any sort of collision has occurred.
func (c *Collide) IsColliding() bool {
return c.Top || c.Bottom || c.Left || c.Right ||
c.InFire != "" || c.InWater
}
// ScanBoundingBox scans all of the pixels in a bounding box on the grid and
// returns if any of them intersect with level geometry.
func (c *Collide) ScanBoundingBox(box render.Rect, grid *level.Chunker) bool {
col := GetCollisionBox(box)
// Check all four edges of the box in parallel on different CPU cores.
type jobSide struct {
p1 render.Point // p2 is perpendicular to p1 along a straight edge
p2 render.Point // of the collision box.
side Side
}
jobs := []jobSide{ // We'll scan each side of the bounding box in parallel
{col.Top[0], col.Top[1], Top},
{col.Bottom[0], col.Bottom[1], Bottom},
{col.Left[0], col.Left[1], Left},
{col.Right[0], col.Right[1], Right},
}
var wg sync.WaitGroup
for _, job := range jobs {
wg.Add(1)
job := job
go func() {
defer wg.Done()
c.ScanGridLine(job.p1, job.p2, grid, job.side)
}()
}
wg.Wait()
return c.IsColliding()
}
// ScanGridLine scans all of the pixels between p1 and p2 on the grid and tests
// for any pixels to be set, implying a collision between level geometry and the
// bounding boxes of the doodad.
func (c *Collide) ScanGridLine(p1, p2 render.Point, grid *level.Chunker, side Side) {
// If scanning the top or bottom line, offset the X coordinate by 1 pixel.
// This is because the 4 corners of the bounding box share their corner
// pixel with each side, so the Left and Right edges will check the
// left- and right-most point.
if side == Top || side == Bottom {
p1.X++
p2.X--
}
for point := range render.IterLine(p1, p2) {
if swatch, err := grid.Get(point); err == nil {
// We're intersecting a pixel! If it's a solid one we'll return it
// in our result. If non-solid, we'll collect attributes from it
// and return them in the final result for gameplay behavior.
if swatch.Fire {
c.InFire = swatch.Name
}
if swatch.Water {
c.InWater = true
}
// Non-solid swatches don't collide so don't pay them attention.
if !swatch.Solid {
continue
}
switch side {
case Top:
c.Top = true
c.TopPoint = point
c.TopPixel = swatch
case Bottom:
c.Bottom = true
c.BottomPoint = point
c.BottomPixel = swatch
case Left:
c.Left = true
c.LeftPoint = point
c.LeftPixel = swatch
case Right:
c.Right = true
c.RightPoint = point
c.RightPixel = swatch
}
}
}
}