/**
 * Debugging drawing library
 *
 * Quick way to draw debug geometry. All input should be in world space and
 * will be rendered in the default view. No additional setup required.
 **/

/** Global switch option. */
bool drw_debug_draw_enable = true;
const vec4 drw_debug_default_color = vec4(1.0, 0.0, 0.0, 1.0);

/* -------------------------------------------------------------------- */
/** \name Internals
 * \{ */

uint drw_debug_start_draw(uint v_needed)
{
  uint vertid = atomicAdd(drw_debug_draw_v_count, v_needed);
  /* NOTE: Skip the header manually. */
  vertid += 1;
  return vertid;
}

uint drw_debug_color_pack(vec4 color)
{
  color = clamp(color, 0.0, 1.0);
  uint result = 0;
  result |= uint(color.x * 255.0) << 0u;
  result |= uint(color.y * 255.0) << 8u;
  result |= uint(color.z * 255.0) << 16u;
  result |= uint(color.w * 255.0) << 24u;
  return result;
}

void drw_debug_line(inout uint vertid, vec3 v1, vec3 v2, uint color)
{
  drw_debug_verts_buf[vertid++] = DRWDebugVert(
      floatBitsToUint(v1.x), floatBitsToUint(v1.y), floatBitsToUint(v1.z), color);
  drw_debug_verts_buf[vertid++] = DRWDebugVert(
      floatBitsToUint(v2.x), floatBitsToUint(v2.y), floatBitsToUint(v2.z), color);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name API
 * \{ */

/**
 * Draw a line.
 */
void drw_debug_line(vec3 v1, vec3 v2, vec4 color)
{
  if (!drw_debug_draw_enable) {
    return;
  }
  const uint v_needed = 2;
  uint vertid = drw_debug_start_draw(v_needed);
  if (vertid + v_needed < DRW_DEBUG_DRAW_VERT_MAX) {
    drw_debug_line(vertid, v1, v2, drw_debug_color_pack(color));
  }
}
void drw_debug_line(vec3 v1, vec3 v2)
{
  drw_debug_line(v1, v2, drw_debug_default_color);
}

/**
 * Draw a quad contour.
 */
void drw_debug_quad(vec3 v1, vec3 v2, vec3 v3, vec3 v4, vec4 color)
{
  if (!drw_debug_draw_enable) {
    return;
  }
  const uint v_needed = 8;
  uint vertid = drw_debug_start_draw(v_needed);
  if (vertid + v_needed < DRW_DEBUG_DRAW_VERT_MAX) {
    uint pcolor = drw_debug_color_pack(color);
    drw_debug_line(vertid, v1, v2, pcolor);
    drw_debug_line(vertid, v2, v3, pcolor);
    drw_debug_line(vertid, v3, v4, pcolor);
    drw_debug_line(vertid, v4, v1, pcolor);
  }
}
void drw_debug_quad(vec3 v1, vec3 v2, vec3 v3, vec3 v4)
{
  drw_debug_quad(v1, v2, v3, v4, drw_debug_default_color);
}

/**
 * Draw a point as octahedron wireframe.
 */
void drw_debug_point(vec3 p, float radius, vec4 color)
{
  if (!drw_debug_draw_enable) {
    return;
  }
  vec3 c = vec3(radius, -radius, 0);
  vec3 v1 = p + c.xzz;
  vec3 v2 = p + c.zxz;
  vec3 v3 = p + c.yzz;
  vec3 v4 = p + c.zyz;
  vec3 v5 = p + c.zzx;
  vec3 v6 = p + c.zzy;

  const uint v_needed = 12 * 2;
  uint vertid = drw_debug_start_draw(v_needed);
  if (vertid + v_needed < DRW_DEBUG_DRAW_VERT_MAX) {
    uint pcolor = drw_debug_color_pack(color);
    drw_debug_line(vertid, v1, v2, pcolor);
    drw_debug_line(vertid, v2, v3, pcolor);
    drw_debug_line(vertid, v3, v4, pcolor);
    drw_debug_line(vertid, v4, v1, pcolor);
    drw_debug_line(vertid, v1, v5, pcolor);
    drw_debug_line(vertid, v2, v5, pcolor);
    drw_debug_line(vertid, v3, v5, pcolor);
    drw_debug_line(vertid, v4, v5, pcolor);
    drw_debug_line(vertid, v1, v6, pcolor);
    drw_debug_line(vertid, v2, v6, pcolor);
    drw_debug_line(vertid, v3, v6, pcolor);
    drw_debug_line(vertid, v4, v6, pcolor);
  }
}
void drw_debug_point(vec3 p, float radius)
{
  drw_debug_point(p, radius, drw_debug_default_color);
}
void drw_debug_point(vec3 p)
{
  drw_debug_point(p, 0.01);
}

/**
 * Draw a sphere wireframe as 3 axes circle.
 */
void drw_debug_sphere(vec3 p, float radius, vec4 color)
{
  if (!drw_debug_draw_enable) {
    return;
  }
  const int circle_resolution = 16;
  const uint v_needed = circle_resolution * 2 * 3;
  uint vertid = drw_debug_start_draw(v_needed);
  if (vertid + v_needed < DRW_DEBUG_DRAW_VERT_MAX) {
    uint pcolor = drw_debug_color_pack(color);
    for (int axis = 0; axis < 3; axis++) {
      for (int edge = 0; edge < circle_resolution; edge++) {
        float angle1 = (2.0 * 3.141592) * float(edge + 0) / float(circle_resolution);
        vec3 p1 = vec3(cos(angle1), sin(angle1), 0.0) * radius;
        p1 = vec3(p1[(0 + axis) % 3], p1[(1 + axis) % 3], p1[(2 + axis) % 3]);

        float angle2 = (2.0 * 3.141592) * float(edge + 1) / float(circle_resolution);
        vec3 p2 = vec3(cos(angle2), sin(angle2), 0.0) * radius;
        p2 = vec3(p2[(0 + axis) % 3], p2[(1 + axis) % 3], p2[(2 + axis) % 3]);

        drw_debug_line(vertid, p + p1, p + p2, pcolor);
      }
    }
  }
}
void drw_debug_sphere(vec3 p, float radius)
{
  drw_debug_sphere(p, radius, drw_debug_default_color);
}

/**
 * Draw a matrix transformation as 3 colored axes.
 */
void drw_debug_matrix(mat4 mat, vec4 color)
{
  vec4 p[4] = vec4[4](vec4(0, 0, 0, 1), vec4(1, 0, 0, 1), vec4(0, 1, 0, 1), vec4(0, 0, 1, 1));
  for (int i = 0; i < 4; i++) {
    p[i] = mat * p[i];
    p[i].xyz /= p[i].w;
  }
  drw_debug_line(p[0].xyz, p[0].xyz, vec4(1, 0, 0, 1));
  drw_debug_line(p[0].xyz, p[1].xyz, vec4(0, 1, 0, 1));
  drw_debug_line(p[0].xyz, p[2].xyz, vec4(0, 0, 1, 1));
}
void drw_debug_matrix(mat4 mat)
{
  drw_debug_matrix(mat, drw_debug_default_color);
}

/**
 * Draw a matrix as a 2 units length bounding box, centered on origin.
 */
void drw_debug_matrix_as_bbox(mat4 mat, vec4 color)
{
  vec4 p[8] = vec4[8](vec4(-1, -1, -1, 1),
                      vec4(1, -1, -1, 1),
                      vec4(1, 1, -1, 1),
                      vec4(-1, 1, -1, 1),
                      vec4(-1, -1, 1, 1),
                      vec4(1, -1, 1, 1),
                      vec4(1, 1, 1, 1),
                      vec4(-1, 1, 1, 1));
  for (int i = 0; i < 8; i++) {
    p[i] = mat * p[i];
    p[i].xyz /= p[i].w;
  }
  drw_debug_quad(p[0].xyz, p[1].xyz, p[2].xyz, p[3].xyz, color);
  drw_debug_line(p[0].xyz, p[4].xyz, color);
  drw_debug_line(p[1].xyz, p[5].xyz, color);
  drw_debug_line(p[2].xyz, p[6].xyz, color);
  drw_debug_line(p[3].xyz, p[7].xyz, color);
  drw_debug_quad(p[4].xyz, p[5].xyz, p[6].xyz, p[7].xyz, color);
}
void drw_debug_matrix_as_bbox(mat4 mat)
{
  drw_debug_matrix_as_bbox(mat, drw_debug_default_color);
}

/** \} */