RenderBlockCulling.h

#pragma once
 
#include "RenderBlock.h"
 
#include "ClipmapParameterCalculation.h"
 
namespace Cogs
{
  static bool intersect(const Cogs::Geometry::Frustum & frustum, const BoundingBox & box)
  {
    return Cogs::Geometry::contains(frustum, box) != 0;
  }
 
  static void cullRenderBlocks(const RenderBlock * blocks,
                        bool * visible,
                        const size_t count,
                        const RenderLevel & renderLevel,
                        const ViewVolume & viewVolume,
                        const Vector3d cullOrigin,
                        const float heightExaggeration,
                        const float worldScaleX,
                        const float worldScaleY)
  {
    // Scales raster 
    const Vector2 worldScale = Vector2(worldScaleX, worldScaleY);
    const Vector2 offset = Vector2(static_cast<float>(cullOrigin.x), static_cast<float>(cullOrigin.y));
    const float offsetZ = static_cast<float>(cullOrigin.z);
 
    for (size_t i = 0; i < count; ++i) {
      const RenderBlock & block = blocks[i];
 
      const Vector2 min = block.min * worldScale + offset;
      const Vector2 max = block.max * worldScale + offset;
 
      const float minZ = offsetZ + (renderLevel.terrainLevel->isHeight ? renderLevel.terrainLevel->minZ * heightExaggeration : -1.0f);
      const float maxZ = offsetZ + (renderLevel.terrainLevel->isHeight ? renderLevel.terrainLevel->maxZ * heightExaggeration : 1.0f);
 
      const BoundingBox bbox = { Vector3(min, minZ), Vector3(max, maxZ) };
 
      // Store culling result, override visibility to always true for degenerate mesh.
      visible[i] = block.mesh->width == -1 || intersect(viewVolume.frustum, bbox);
    };
  }
}