From: Matthew Owens <matthew@owens.tech>
Date: Fri, 2 Oct 2020 14:26:37 +0000 (+0100)
Subject: moved collisions to their own file & added ball/paddle collision response
X-Git-Url: https://git.owens.tech/assets/112-editable-focus.html/assets/112-editable-focus.html/git?a=commitdiff_plain;h=ffc97facfdcc5fecac3418fcdd869b9d61f7999b;p=pong.git
moved collisions to their own file & added ball/paddle collision response
---
diff --git a/src/collision.c b/src/collision.c
new file mode 100644
index 0000000..4682ece
--- /dev/null
+++ b/src/collision.c
@@ -0,0 +1,32 @@
+#include "collision.h"
+
+bool ll_collision(float x1, float y1, float x2, float y2,
+ float x3, float y3, float x4, float y4, Vec2df *intersect)
+{
+ float uA = ((x4-x3)*(y1-y3) - (y4-y3)*(x1-x3)) /
+ ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
+ float uB = ((x2-x1)*(y1-y3) - (y2-y1)*(x1-x3)) /
+ ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
+
+ if(intersect) {
+ intersect->x = x1 + (uA * (x2-x1));
+ intersect->y = y1 + (uB * (y2-y1));
+ }
+
+ return (uA >= 0 && uA <= 1 && uB >= 0 && uB <= 1);
+}
+
+/*
+ * (v)box / line collision
+ * returns 0 on no collision, 1/2/3/4 on left/right/top/bottom
+ */
+int lr_collision(Vec2df start, Vec2df end, SDL_Rect r, Vec2df *i) {
+ if(ll_collision(start.x, start.y, end.x, end.y, r.x, r.y, r.x, r.y + r.h, i))
+ return 1; //left
+ if(ll_collision(start.x, start.y, end.x, end.y, r.x + r.w, r.y, r.x + r.w, r.y + r.h, i))
+ return 2; //right
+ if(ll_collision(start.x, start.y, end.x, end.y, r.x, r.y, r.x + r.w, r.y , i))
+ return 3; //top
+ if(ll_collision(start.x, start.y, end.x, end.y, r.x, r.y + r.h, r.x + r.w, r.y + r.h, i))
+ return 4; //bottom
+}
diff --git a/src/collision.h b/src/collision.h
new file mode 100644
index 0000000..38111a8
--- /dev/null
+++ b/src/collision.h
@@ -0,0 +1,8 @@
+#pragma once
+#include <SDL2/SDL.h>
+#include <stdbool.h>
+#include "vec2d.h"
+
+bool ll_collision(float x1, float y1, float x2, float y2,
+ float x3, float y3, float x4, float y4, Vec2df *intersect);
+int lr_collision(Vec2df start, Vec2df end, SDL_Rect r, Vec2df *i);
diff --git a/src/main.c b/src/main.c
index e200376..8eb04c4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4,16 +4,8 @@
#include <SDL2/SDL.h>
#include <stdbool.h>
#include "timestep.h"
-
-typedef struct Vec2di {
- int x;
- int y;
-} Vec2di;
-
-typedef struct Vec2df {
- float x;
- float y;
-} Vec2df;
+#include "collision.h"
+#include "vec2d.h"
typedef struct Colour {
Uint8 r;
@@ -90,36 +82,6 @@ static void vbox_render(const Vbox *b)
SDL_RenderFillRect(renderer, &b->r);
}
-static bool ll_collision(float x1, float y1, float x2, float y2,
- float x3, float y3, float x4, float y4, Vec2df *intersect)
-{
- float uA = ((x4-x3)*(y1-y3) - (y4-y3)*(x1-x3)) /
- ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
- float uB = ((x2-x1)*(y1-y3) - (y2-y1)*(x1-x3)) /
- ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
-
- if(intersect) {
- intersect->x = x1 + (uA * (x2-x1));
- intersect->y = y1 + (uB * (y2-y1));
- }
-
- return (uA >= 0 && uA <= 1 && uB >= 0 && uB <= 1);
-}
-
-/*
- * (v)box / line collision
- * returns 0 on no collision, 1/2/3/4 on left/right/top/bottom
- */
-static int lr_collision(Vec2df start, Vec2df end, SDL_Rect r, Vec2df *i) {
- if(ll_collision(start.x, start.y, end.x, end.y, r.x, r.y, r.x, r.y + r.h, i))
- return 1; //left
- if(ll_collision(start.x, start.y, end.x, end.y, r.x + r.w, r.y, r.x + r.w, r.y + r.h, i))
- return 2; //right
- if(ll_collision(start.x, start.y, end.x, end.y, r.x, r.y, r.x + r.w, r.y , i))
- return 3; //top
- if(ll_collision(start.x, start.y, end.x, end.y, r.x, r.y + r.h, r.x + r.w, r.y + r.h, i))
- return 4; //bottom
-}
static void paddle_update(const Uint8* keyStates, float dt)
{
@@ -146,10 +108,6 @@ static void ball_update(float dt)
float halfw = ball.r.w / 2;
float halfh = ball.r.h / 2;
- // applying velocity
- ball.r.x += ball.v.x * dt;
- ball.r.y += ball.v.y * dt;
-
// velocity projection start to center of ball
vline[0].x = ball.r.x + halfw;
vline[0].y = ball.r.y + halfh;
@@ -165,17 +123,41 @@ static void ball_update(float dt)
// are we going to collide with the paddle?
{
int willCollide = lr_collision(vline[0], vline[1], pad.r, NULL);
+ // left/right/top/bottom
switch(willCollide) {
//TODO: set ball loc to colliding wall, invert vel & skip vel add
+ case 1:
+ ball.r.x = pad.r.x - ball.r.w;
+ ball.v.x *= -1;
+ break;
+ case 2:
+ ball.r.x = pad.r.x + pad.r.w;
+ ball.v.x *= -1;
+ break;
+ case 3:
+ ball.r.y = pad.r.y - ball.r.h;
+ ball.v.y *= -1;
+ break;
+ case 4:
+ ball.r.y = pad.r.y + pad.r.h;
+ ball.v.y *= -1;
+ break;
}
+ if(willCollide != 0) { collisionResponded = true; }
+ }
+
+ // applying velocity if needed
+ if(!collisionResponded) {
+ ball.r.x += ball.v.x * dt;
+ ball.r.y += ball.v.y * dt;
}
// screen bounds checks & responses
- if(ball.r.x + ball.r.w > windowSize.x && !collisionResponded){
+ if(ball.r.x + ball.r.w > windowSize.x){
ball.r.x = windowSize.x - ball.r.w;
ball.v.x *= -1;
}
- if(ball.r.y + ball.r.h > windowSize.y && !collisionResponded){
+ if(ball.r.y + ball.r.h > windowSize.y){
ball.r.y = windowSize.y - ball.r.h;
ball.v.y *= -1;
}
diff --git a/src/vec2d.h b/src/vec2d.h
new file mode 100644
index 0000000..664718b
--- /dev/null
+++ b/src/vec2d.h
@@ -0,0 +1,12 @@
+#pragma once
+
+typedef struct Vec2di {
+ int x;
+ int y;
+} Vec2di;
+
+typedef struct Vec2df {
+ float x;
+ float y;
+} Vec2df;
+