#version 300 es
// frost patch — a flat quad the fragment stage carves into a mottled disc. it needs two things the
// builtin varyings do not carry: the instance CENTER (to measure a radial falloff in world space)
// and the instance RADIUS. both ride along as extra varyings
layout(location = 0) in vec3 aPos;
layout(location = 1) in vec3 aNormal;
layout(location = 2) in vec4 aInstRot;
layout(location = 3) in vec3 aInstPos;
layout(location = 4) in vec3 aInstScale;
layout(location = 5) in vec4 aInstColor;
layout(location = 6) in vec4 aInstParams;
#include "_graphics_uniforms.glsl"
out highp vec3 vWorldPos;
out highp vec3 vCenter;
out vec4 vColor;
out float vEmissive;
out float vRadius;
vec3 quatRotate(vec4 q, vec3 v) {
    return v + 2.0 * cross(q.xyz, cross(q.xyz, v) + q.w * v);
}
void main() {
    vec3 world = quatRotate(aInstRot, aPos * aInstScale) + aInstPos;
    gl_Position = u_viewProjection * vec4(world, 1.0);
    vWorldPos = world;
    vCenter   = aInstPos;
    vColor    = aInstColor;
    vEmissive = aInstParams.x;
    vRadius   = aInstScale.x;
}