abstreet/widgetry/shaders/vertex_webgl1.glsl

56 lines
1.6 KiB
GLSL

#version 100
precision mediump float;
precision mediump sampler2D;
// (x offset, y offset, zoom)
uniform vec3 transform;
// (window width, window height, z value)
uniform vec3 window;
// in
attribute vec3 position;
attribute vec4 color;
attribute float texture_index;
// out
varying vec4 fs_color;
varying vec3 fs_texture_coord;
void main() {
fs_color = color;
float zoom = transform[2];
// This is map_to_screen
float screen_x = (position[0] * zoom) - transform[0];
float screen_y = (position[1] * zoom) - transform[1];
// Translate position to normalized device coordinates (NDC)
float x = (screen_x / window[0] * 2.0) - 1.0;
float y = (screen_y / window[1] * 2.0) - 1.0;
// largest absolute value for layer base z values in drawing.rs (i.e.
// MAPSPACE_Z vs. TOOLTIP_Z)
float z_range = 2.0;
// we increment z up to 1.0 to affect ordering within a layer, so consider
// that when scaling z to NDC too
float z_scale = z_range + 1.0;
float z = (position[2] + window[2]) / z_scale;
// Note the y inversion
gl_Position = vec4(x, -y, z, 1.0);
// An arbitrary factor to scale the textures we're using.
//
// The proper value depends on the design of the particular sprite sheet.
// If we want to support multiple sprite sheets, this could become a
// uniform, or a vertex attribute depending on how we expect it to change.
float texture_scale = 16.0;
float t_x = ((position[0] * zoom)) / texture_scale / zoom;
float t_y = ((position[1] * zoom)) / texture_scale / zoom;
fs_texture_coord = vec3(vec2(t_x, t_y), texture_index);
}