146 lines
3.7 KiB
Plaintext
146 lines
3.7 KiB
Plaintext
struct InstanceInput {
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@location(2) position: vec3<f32>,
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@location(3) size: f32,
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@location(4) tint: vec2<f32>,
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};
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struct VertexInput {
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@location(0) position: vec3<f32>,
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@location(1) texture_coords: vec2<f32>,
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}
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struct VertexOutput {
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@builtin(position) position: vec4<f32>,
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@location(0) texture_coords: vec2<f32>,
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@location(1) tint: vec2<f32>,
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}
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@group(1) @binding(0)
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var<uniform> global: GlobalUniform;
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struct GlobalUniform {
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camera_position: vec2<f32>,
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camera_zoom: vec2<f32>,
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camera_zoom_limits: vec2<f32>,
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window_size: vec2<f32>,
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window_aspect: vec2<f32>,
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starfield_texture: vec2<u32>,
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starfield_tile_size: vec2<f32>,
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starfield_size_limits: vec2<f32>,
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};
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@group(0) @binding(0)
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var texture_array: binding_array<texture_2d<f32>>;
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@group(0) @binding(1)
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var sampler_array: binding_array<sampler>;
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fn fmod(x: vec2<f32>, m: f32) -> vec2<f32> {
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return x - floor(x / m) * m;
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}
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@vertex
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fn vertex_main(
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vertex: VertexInput,
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instance: InstanceInput,
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) -> VertexOutput {
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var out: VertexOutput;
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out.texture_coords = vertex.texture_coords;
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out.tint = instance.tint;
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// Center of the tile the camera is currently in, in game coordinates.
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// x div y = x - (x mod y)
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let tile_center = (
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global.camera_position.xy
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- (
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fmod(
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global.camera_position.xy + global.starfield_tile_size.x / 2.0,
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global.starfield_tile_size.x
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) - global.starfield_tile_size.x / 2.0
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)
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);
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let zoom_min_times = (
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global.camera_zoom.x / global.camera_zoom_limits.x
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);
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// Hide n% of the smallest stars
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// If we wanted a constant number of stars on the screen, we would do
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// `let hide_fraction = 1.0 - 1.0 / (zoom_min_times * zoom_min_times);`
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// We, however, don't want this: a bigger screen should have more stars,
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// but not *too* many. We thus scale linearly.
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let hide_fraction = 1.0 - 1.0 / (zoom_min_times * 0.8);
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if (
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instance.size < (
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hide_fraction * (global.starfield_size_limits.y - global.starfield_size_limits.x)
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+ (global.starfield_size_limits.x)
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)
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) {
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out.position = vec4<f32>(2.0, 2.0, 0.0, 1.0);
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return out;
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}
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// Apply sprite aspect ratio & scale factor
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// also applies screen aspect ratio
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// Note that we do NOT scale for distance here---this is intentional.
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var scale: f32 = instance.size / global.camera_zoom.x;
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// Minimum scale to prevent flicker at large zoom levels
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var real_size = scale * global.window_size.xy;
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if (real_size.x < 2.0 || real_size.y < 2.0) {
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// Otherwise, clamp to a minimum scale
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scale = 2.0 / max(global.window_size.x, global.window_size.y);
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}
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// Divide by two, because viewport height is 2 in screen units
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// (coordinates go from -1 to 1)
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var pos: vec2<f32> = vec2<f32>(
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vertex.position.x * (scale/2.0) / global.window_aspect.x,
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vertex.position.y * (scale/2.0)
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);
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// World position relative to camera
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// (Note that instance position is in a different
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// coordinate system than usual)
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let camera_pos = (instance.position.xy + tile_center) - global.camera_position.xy;
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// Translate
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pos = pos + (
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// Don't forget to correct distance for screen aspect ratio too!
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(camera_pos / (global.camera_zoom.x * instance.position.z))
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/ vec2<f32>(global.window_aspect.x, 1.0)
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);
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out.position = vec4<f32>(pos, 0.0, 1.0) * instance.position.z;
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return out;
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}
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@fragment
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fn fragment_main(in: VertexOutput) -> @location(0) vec4<f32> {
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let b = 0.8 - (in.tint.x / 1.5); // brightness
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let c = in.tint.y; // color
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// TODO: saturation
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// TODO: more subtle starfield
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// TODO: blur stars more?
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let c_top = vec3<f32>(0.369, 0.819, 0.796);
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let c_bot = vec3<f32>(0.979, 0.556, 0.556);
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let c_del = c_bot - c_top;
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return textureSampleLevel(
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texture_array[global.starfield_texture.x],
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sampler_array[0],
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in.texture_coords,
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0.0
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).rgba * vec4<f32>(
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(c_top + (c_del * c)) * b,
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1.0
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);
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} |