SPG:Springs and Things

Springboards

Red springboards propel Sonic at a speed of 16, and yellow springboards at a speed of 10. If the springboard faces up or down, the value is either negative or positive, respectively, and Y speed is set to it. If the springboard faces left or right, the value is either negative or positive, respectively, and X speed is set to it. Vertical springboards don't affect X speed and likewise horizontal springboards don't affect Y speed.

Diagonal Springboards

There are no diagonal springboards in Sonic the Hedgehog (16-bit). But there are in Sonic 2 (16-bit), 3, K, and CD. Sonic 2, 3, and K work the same way, but Sonic CD is different.

In Sonic 2, 3, and K, a diagonal spring sets both X speed and Y speed to the springboard's value, with the appropriate sign. So a red springboard facing up and to the right sets Y speed to -16 and X speed to 16. The trouble with this method is that Sonic is technically bounced faster diagonally than horizontally or vertically. This is because they didn't bother to calculate the sine functions.

In Sonic CD, they do however. Conveniently, the absolute sine and cosine of a 45 degree angle are the same, so you only need one value. It comes out to 11.3125 for Red springs and 7.0703125 for Yellow ones.

Balloons

The balloons in Carnival Night Zone set Y speed to -7 when Sonic collides with them, no matter what his angle of collision. X speed is not affected.

Bobbins

The bobbins in Spring Yard Zone set Sonic's X speed to 7*cosine(p), and Y speed to 7*-sine(p), where p is the angle measured from the bobbin's centre to Sonic's. This is regardless of Sonic's velocity when he hits the bobbin.

Cannons

The cannons in Carnival Night Zone set Sonic's X speed to 16*cosine(p), and Y speed to 16*-sine(p), where p is the angle of the cannon.

Spring Caps

The red spring caps that cover the tubes in Chemical Plant Zone work like springboards, but are slightly stronger than a Yellow springboard. They set Sonic's Y speed to -10.5 upon collision.

Spinners

The black spinners that impel you forward in Chemical Plant Zone set X speed to 16. They don't seem to slow you down if you're already moving faster than that, though.

Ski Lifts

The ski lifts in Hill Top Zone move with an X speed of 2, and a Y speed of 1.

Mushrooms

The mushrooms in Mushroom Hill Zone work just like springboards, only each successive bounce is higher than the last, up to three bounces. The first bounce sets Y speed to -6.5, the second, -7.5, and the third, -8.5.

Breaking Walls and Objects

X speed is unaffected when rolling through Monitors, Badniks, or walls in Sonic 1.

However, when Knuckles breaks walls in Sonic 3 & Knuckles, though his X speed is unaffected, he doesn't move during the frame in which he hits the wall. The same thing is true when Sonic spindashes through a wall in Sonic 3 & Knuckles.

Breakable Blocks and Rocks

When Sonic jumps on top of breakable objects, such as the rocks in Hill Top Zone, blocks in Marble Zone, or the tube caps in Chemical Plant Zone, he bounces away with a Y speed of -3. X speed is unaffected.