Animate a pendulum: Difference between revisions
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→{{header|Wren}}: Changed to Wren S/H
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}
</syntaxhighlight>
=={{header|FutureBasic}}==
<syntaxhighlight lang="futurebasic">
void local fn BuildWindow
window 1, @"Animated Pendulum in FutureBasic", ( 0, 0, 640, 400 )
WindowSetBackgroundColor( 1, fn ColorBlack )
WindowSetMinSize( 1, fn CGSizeMake( 640, 400 ) )
WindowSetMaxSize( 1, fn CGSizeMake( 640, 400 ) )
end fn
local fn AnimatedPendulum
block double theta, gravity, length, accel, speed, weight, tempo, px, py, bx, by
block ColorRef color = fn ColorWithRGB( 0.164, 0.793, 0.075, 1.0 )
theta = pi/2.0 // Denominator of 2.0 = 180-degree swing, < 2.0 narrows inscribed arc, > 2.0 widens it.
gravity = 9.90 // Adjusts effect of gravity on swing. Smaller values slow arc swing.
length = 0.95 // Tweak for length of pendulum arm
speed = 0 // Zero this or you get a propellor!
px = 320 // Pivot horizontal center x point (half window width)
py = 30 // Pivot y center y point from top
weight = 42 // Diameter of pendulum weight
tempo = 75 // Smaller value increases pendulum tempo, larger value slows it.
timerbegin, 0.02, YES
bx = px + length * 300 * sin(theta) // Pendulum bottom x point
by = py - length * 300 * cos(theta) // Pendulum bottom y point
cls
pen 6.0, color
line px, py to bx, by
oval fill bx -weight/2, by -weight/2, weight, weight, color // Traveling weight
pen 4.0
oval fill 313, 20, 16, 16, fn ColorGray // Top center point
accel = gravity * sin(theta) / length / tempo
speed += accel / tempo
theta += speed
timerEnd
end fn
void local fn DoDialog( ev as long, tag as long, wnd as long )
select ( ev )
case _windowWillClose : end
end select
end fn
on dialog fn DoDialog
fn BuildWindow
fn AnimatedPendulum
HandleEvents
</syntaxhighlight>
[[File:Animated_Pendulum_FutureBasic2.gif]]
=={{header|Go}}==
Line 2,654 ⟶ 2,705:
animate(muv, [Scene(muv, backdrop),
Scene(muv, frame, easingfunction=easeinoutcubic)],
creategif=true, pathname=giffilename)</syntaxhighlight>
{{out}}
[[File:Pendulum animation.gif|320px]]
<pre>
</pre>
=={{header|Kotlin}}==
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{{libheader|DOME}}
{{libheader|Wren-dynamic}}
<syntaxhighlight lang="
import "dome" for Window
import "math" for Math
Line 5,551 ⟶ 5,605:
exit</syntaxhighlight>
=={{header|Zig}}==
{{libheader|Raylib}}
{{works with|Zig|0.11.0dev}} {{works with|Raylib|4.6dev}}
{{trans|Nim}}
<syntaxhighlight lang="zig">const math = @import("std").math;
const c = @cImport({
@cInclude("raylib.h");
});</syntaxhighlight>
<syntaxhighlight lang="zig">pub fn main() void {
c.SetConfigFlags(c.FLAG_VSYNC_HINT);
c.InitWindow(640, 320, "Pendulum");
defer c.CloseWindow();
// Simulation constants.
const g = 9.81; // Gravity (should be positive).
const length = 5.0; // Pendulum length.
const theta0 = math.pi / 3.0; // Initial angle for which omega = 0.
const e = g * length * (1 - @cos(theta0)); // Total energy = potential energy when starting.
// Simulation variables.
var theta: f32 = theta0; // Current angle.
var omega: f32 = 0; // Angular velocity = derivative of theta.
var accel: f32 = -g / length * @sin(theta0); // Angular acceleration = derivative of omega.
c.SetTargetFPS(60);
while (!c.WindowShouldClose()) // Detect window close button or ESC key
{
const half_width = @as(f32, @floatFromInt(c.GetScreenWidth())) / 2;
const pivot = c.Vector2{ .x = half_width, .y = 0 };
// Compute the position of the mass.
const mass = c.Vector2{
.x = 300 * @sin(theta) + pivot.x,
.y = 300 * @cos(theta),
};
{
c.BeginDrawing();
defer c.EndDrawing();
c.ClearBackground(c.RAYWHITE);
c.DrawLineV(pivot, mass, c.GRAY);
c.DrawCircleV(mass, 20, c.GRAY);
}
// Update theta and omega.
const dt = c.GetFrameTime();
theta += (omega + dt * accel / 2) * dt;
omega += accel * dt;
// If, due to computation errors, potential energy is greater than total energy,
// reset theta to ±theta0 and omega to 0.
if (length * g * (1 - @cos(theta)) >= e) {
theta = math.sign(theta) * theta0;
omega = 0;
}
accel = -g / length * @sin(theta);
}
}</syntaxhighlight>
=={{header|ZX Spectrum Basic}}==
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