#version 450

// Static-map model vertex stage. Draws the world-space triangle soup built by
// ra3::models (buildings and props the map places) against the exact camera the
// terrain raymarcher uses, so both passes share one projection and depth test.
//
// The camera is passed as its orthonormal basis so the same math as
// terrain.frag applies: ndc.x = dot(r, right) / (a * tan(fov/2) * aspect),
// ndc.y = -dot(r, up) / (a * tan(fov/2)), depth = (a - NEAR) / (FAR - NEAR)
// with `a = dot(r, fwd)` the view-space depth.

layout(location = 0) in vec3 in_pos;
layout(location = 1) in vec3 in_normal;
layout(location = 2) in vec2 in_uv;
layout(location = 3) in float in_layer;

layout(push_constant) uniform Push {
    vec4 cam_pos; // xyz = eye position
    vec4 fwd;     // xyz = forward
    vec4 right;   // xyz = right, w = tan(fov / 2)
    vec4 up;      // xyz = up,    w = tan(fov / 2) * aspect
    vec4 sun;     // xyz = sun direction, w = ambient
} pc;

layout(location = 0) out vec2 out_uv;
layout(location = 1) out vec3 out_normal;
layout(location = 2) flat out float out_layer;

const float NEAR = 10.0;
const float FAR = 60000.0;

void main() {
    vec3 r = in_pos - pc.cam_pos.xyz;
    float a = dot(r, pc.fwd.xyz);
    float b = dot(r, pc.right.xyz);
    float c = dot(r, pc.up.xyz);
    float th = pc.right.w;
    float th_aspect = pc.up.w;
    float depth = clamp((a - NEAR) / (FAR - NEAR), 0.0, 1.0);
    gl_Position = vec4(b / th_aspect, -c / th, depth * a, a);
    out_uv = in_uv;
    out_normal = in_normal;
    out_layer = in_layer;
}