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const std = @import("std");
const matrix = @import("matrix.zig");
const sdl = @import("sdl.zig");
const ArenaAllocator = std.heap.ArenaAllocator;
const Cube = struct {
points: [8]Point,
};
pub const Point = struct {
x: f32,
y: f32,
z: f32,
};
pub fn draw_cube(instance: sdl.instance, cube: Cube) void {
sdl.draw_color(instance, 255, 255, 255, 0);
sdl.draw_line(instance, cube.points[0], cube.points[1]);
sdl.draw_line(instance, cube.points[0], cube.points[2]);
sdl.draw_line(instance, cube.points[0], cube.points[4]);
sdl.draw_line(instance, cube.points[7], cube.points[6]);
sdl.draw_line(instance, cube.points[7], cube.points[5]);
sdl.draw_line(instance, cube.points[7], cube.points[3]);
sdl.draw_line(instance, cube.points[2], cube.points[3]);
sdl.draw_line(instance, cube.points[4], cube.points[5]);
sdl.draw_line(instance, cube.points[1], cube.points[5]);
sdl.draw_line(instance, cube.points[6], cube.points[2]);
sdl.draw_line(instance, cube.points[3], cube.points[1]);
sdl.draw_line(instance, cube.points[4], cube.points[6]);
}
pub fn shift_cube(cube: Cube, x: f32, y: f32, z: f32) Cube {
var shifted_cube = Cube{ .points = undefined };
for (cube.points) |point, i| {
shifted_cube.points[i].x = point.x + x;
shifted_cube.points[i].y = point.y + y;
shifted_cube.points[i].z = point.z + z;
}
return shifted_cube;
}
pub fn center_cube(cube: Cube, offset: f32) Cube {
var centered_cube = Cube{ .points = undefined };
for (cube.points) |point, i| {
centered_cube.points[i] = center_point(point, offset);
}
return centered_cube;
}
pub fn center_point(point: Point, offset: f32) Point {
return Point{
.x = point.x + offset,
.y = point.y + offset,
.z = 0,
};
}
pub fn rotate_cube(arena: *ArenaAllocator, cube: Cube, alpha: f32, beta: f32) Cube {
var rotated_cube = Cube{ .points = undefined };
for (cube.points) |point, i| {
rotated_cube.points[i] = rotate_point(arena, point, alpha, beta);
}
return rotated_cube;
}
pub fn rotate_point(arena: *ArenaAllocator, point: Point, alpha: f32, beta: f32) Point {
var a = matrix.new(
arena,
3,
3,
&[_]f32{
1, 0, 0,
0, @cos(alpha), @sin(alpha),
0, -@sin(alpha), @cos(alpha),
},
);
var b = matrix.new(
arena,
3,
3,
&[_]f32{
@cos(beta), 0, -@sin(beta),
0, 1, 0,
@sin(beta), 0, @cos(beta),
},
);
var m = matrix.multiply(
arena,
matrix.multiply(arena, a, b),
matrix.new(arena, 3, 1, &[3]f32{ point.x, point.y, point.z }),
);
return Point{
.x = m.x.items[0],
.y = m.x.items[1],
.z = m.x.items[2],
};
}
pub fn project_cube(arena: *ArenaAllocator, cube: Cube) Cube {
var projected_cube = Cube{ .points = undefined };
for (cube.points) |point, i| {
projected_cube.points[i] = project_point(arena, point);
}
return projected_cube;
}
pub fn project_point(arena: *ArenaAllocator, p: Point) Point {
var cx = [_]f32{
1, 0, 0,
0, 1, 0,
0, 0, 0,
};
var c = matrix.new(arena, 3, 3, &cx);
var m = matrix.multiply(arena, c, matrix.new(arena, 3, 1, &[3]f32{ p.x, p.y, p.z }));
return Point{
.x = m.x.items[0],
.y = m.x.items[1],
.z = m.x.items[2],
};
}
pub fn scale_cube(cube: Cube, scale: f32) Cube {
var scaled_cube = Cube{ .points = undefined };
for (cube.points) |point, i| {
scaled_cube.points[i].x = point.x * scale;
scaled_cube.points[i].y = point.y * scale;
scaled_cube.points[i].z = point.z * scale;
}
return scaled_cube;
}
pub fn draw_axis(arena: *ArenaAllocator, instance: sdl.instance) void {
var o = center_point(
project_point(arena, Point{ .x = 0, .y = 0, .z = 0 }),
250,
);
var x = center_point(
project_point(arena, Point{ .x = 50, .y = 0, .z = 0 }),
250,
);
var y = center_point(
project_point(arena, Point{ .x = 0, .y = 50, .z = 0 }),
250,
);
var z = center_point(
project_point(arena, Point{ .x = 0, .y = 0, .z = 50 }),
250,
);
sdl.draw_color(instance, 255, 0, 0, 0);
sdl.draw_line(instance, o, x);
sdl.draw_color(instance, 0, 255, 0, 0);
sdl.draw_line(instance, o, y);
sdl.draw_color(instance, 0, 0, 255, 0);
sdl.draw_line(instance, o, z);
}
pub fn main() anyerror!void {
var instance = sdl.init();
const unit_cube = Cube{
.points = [8]Point{
Point{ .x = 1, .y = 1, .z = 1 },
Point{ .x = 1, .y = 1, .z = -1 },
Point{ .x = 1, .y = -1, .z = 1 },
Point{ .x = 1, .y = -1, .z = -1 },
Point{ .x = -1, .y = 1, .z = 1 },
Point{ .x = -1, .y = 1, .z = -1 },
Point{ .x = -1, .y = -1, .z = 1 },
Point{ .x = -1, .y = -1, .z = -1 },
},
};
var beta: f32 = 0;
var alpha: f32 = 0;
while (true) {
var arena = ArenaAllocator.init(std.heap.page_allocator);
var event = sdl.get_event();
if (event.mode == sdl.modes.quit) {
break;
} else if (event.mode == sdl.modes.key) {
switch (event.key) {
sdl.keys.q => break,
else => continue,
}
}
sdl.draw_color(instance, 0, 0, 0, 0);
sdl.clear(instance);
draw_axis(&arena, instance);
var cube = rotate_cube(&arena, unit_cube, alpha, beta);
cube = scale_cube(cube, 50);
cube = project_cube(&arena, cube);
cube = center_cube(cube, 250);
draw_cube(instance, cube);
cube = rotate_cube(&arena, unit_cube, alpha + 90, beta + 90);
cube = scale_cube(cube, 25);
cube = project_cube(&arena, cube);
cube = center_cube(cube, 250);
draw_cube(instance, cube);
cube = shift_cube(unit_cube, 5, 0, 0);
cube = rotate_cube(&arena, cube, 2 * alpha, 2 * beta);
cube = scale_cube(cube, 25);
cube = project_cube(&arena, cube);
cube = center_cube(cube, 250);
draw_cube(instance, cube);
cube = shift_cube(unit_cube, -5, 0, 0);
cube = rotate_cube(&arena, cube, 2 * alpha, 2 * beta);
cube = scale_cube(cube, 25);
cube = project_cube(&arena, cube);
cube = center_cube(cube, 250);
draw_cube(instance, cube);
beta += 0.01;
alpha += 0.01;
arena.deinit();
sdl.present(instance);
sdl.delay(10);
}
sdl.quit(instance);
}
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