Unity3D技术文档翻译
上一章：【Unity3D技术文档翻译】第3.6.6.2篇 放置光照探针
本章原文所在章节：【Unity Manual】→【Graphics】→【Graphics Overview】→【Lighting】→【Global Illumination】→【Light Probes】→【Placing probes using scripting】
使用脚本放置光照探针
在大型场景中手动摆放光照探针会很消耗时间。你可以通过编写你自己的编辑器脚本来自动放置光照探针。你的脚本将能够创建一个新的 GameObject，并添加一个 LightProbeGroup 组件，然后你可以根据你想要制定的规则来添加探针坐标。
举个例子，下面这段脚本将按照圆圈状放置光照探针。
using UnityEngine;
using System.Collections.Generic;
[RequireComponent (typeof (LightProbeGroup))]
public class LightProbesTetrahedralGrid : MonoBehaviour
{
// Common
public float m_Side = 1.0f;
public float m_Radius = 5.0f;
public float m_InnerRadius = 0.1f;
public float m_Height = 2.0f;
public uint m_Levels = 3;
const float kMinSide = 0.05f;
const float kMinHeight = 0.05f;
const float kMinInnerRadius = 0.1f;
const uint kMinIterations = 4;
public void OnValidate ()
{
m_Side = Mathf.Max (kMinSide, m_Side);
m_Height = Mathf.Max (kMinHeight, m_Height);
if (m_InnerRadius < kMinInnerRadius)
{
TriangleProps props = new TriangleProps (m_Side);
m_Radius = Mathf.Max (props.circumscribedCircleRadius + 0.01f, m_Radius);
}
else
{
m_Radius = Mathf.Max (0.1f, m_Radius);
m_InnerRadius = Mathf.Min (m_Radius, m_InnerRadius);
}
}
struct TriangleProps
{
public TriangleProps (float triangleSide)
{
side = triangleSide;
halfSide = side / 2.0f;
height = Mathf.Sqrt (3.0f) * side / 2.0f;
inscribedCircleRadius = Mathf.Sqrt (3.0f) * side / 6.0f;
circumscribedCircleRadius = 2.0f * height / 3.0f;
}
public float side;
public float halfSide;
public float height;
public float inscribedCircleRadius;
public float circumscribedCircleRadius;
};
private TriangleProps m_TriangleProps;
public void Generate ()
{
LightProbeGroup lightProbeGroup = GetComponent<LightProbeGroup> ();
List<Vector3> positions = new List<Vector3> ();
m_TriangleProps = new TriangleProps (m_Side);
if (m_InnerRadius < kMinInnerRadius)
GenerateCylinder (m_TriangleProps, m_Radius, m_Height, m_Levels, positions);
else
GenerateRing (m_TriangleProps, m_Radius, m_InnerRadius, m_Height, m_Levels, positions);
lightProbeGroup.probePositions = positions.ToArray ();
}
static void AttemptAdding (Vector3 position, Vector3 center, float distanceCutoffSquared, List<Vector3> outPositions)
{
if ((position - center).sqrMagnitude < distanceCutoffSquared)
outPositions.Add (position);
}
uint CalculateCylinderIterations (TriangleProps props, float radius)
{
int iterations = Mathf.CeilToInt ((radius + props.height - props.inscribedCircleRadius) / props.height);
if (iterations > 0)
return (uint)iterations;
return 0;
}
void GenerateCylinder (TriangleProps props, float radius, float height, uint levels, List<Vector3> outPositions)
{
uint iterations = CalculateCylinderIterations (props, radius);
float distanceCutoff = radius;
float distanceCutoffSquared = distanceCutoff * distanceCutoff;
Vector3 up = new Vector3 (props.circumscribedCircleRadius, 0.0f, 0.0f);
Vector3 leftDown = new Vector3 (-props.inscribedCircleRadius, 0.0f, -props.halfSide);
Vector3 rightDown = new Vector3 (-props.inscribedCircleRadius, 0.0f, props.halfSide);
for (uint l = 0; l < levels; l++)
{
float tLevel = levels == 1 ? 0 : (float)l / (float)(levels - 1);
Vector3 center = new Vector3 (0.0f, tLevel * height, 0.0f);
if (l % 2 == 0)
{
for (uint i = 0; i < iterations; i++)
{
Vector3 upCorner = center + up + (float)i * up * 2.0f * 3.0f / 2.0f;
Vector3 leftDownCorner = center + leftDown + (float)i * leftDown * 2.0f * 3.0f / 2.0f;
Vector3 rightDownCorner = center + rightDown + (float)i * rightDown * 2.0f * 3.0f / 2.0f;
AttemptAdding (upCorner, center, distanceCutoffSquared, outPositions);
AttemptAdding (leftDownCorner, center, distanceCutoffSquared, outPositions);
AttemptAdding (rightDownCorner, center, distanceCutoffSquared, outPositions);
Vector3 leftDownUp = upCorner - leftDownCorner;
Vector3 upRightDown = rightDownCorner - upCorner;
Vector3 rightDownLeftDown = leftDownCorner - rightDownCorner;
uint subdiv = 3 * i + 1;
for (uint s = 1; s < subdiv; s++)
{
Vector3 leftDownUpSubdiv = leftDownCorner + leftDownUp * (float)s / (float)subdiv;
AttemptAdding (leftDownUpSubdiv, center, distanceCutoffSquared, outPositions);
Vector3 upRightDownSubdiv = upCorner + upRightDown * (float)s / (float)subdiv;
AttemptAdding (upRightDownSubdiv, center, distanceCutoffSquared, outPositions);
Vector3 rightDownLeftDownSubdiv = rightDownCorner + rightDownLeftDown * (float)s / (float)subdiv;
AttemptAdding (rightDownLeftDownSubdiv, center, distanceCutoffSquared, outPositions);
}
}
}
else
{
for (uint i = 0; i < iterations; i++)
{
Vector3 upCorner = center + (float)i * (2.0f * up * 3.0f / 2.0f);
Vector3 leftDownCorner = center + (float)i * (2.0f * leftDown * 3.0f / 2.0f);
Vector3 rightDownCorner = center + (float)i * (2.0f * rightDown * 3.0f / 2.0f);
AttemptAdding (upCorner, center, distanceCutoffSquared, outPositions);
AttemptAdding (leftDownCorner, center, distanceCutoffSquared, outPositions);
AttemptAdding (rightDownCorner, center, distanceCutoffSquared, outPositions);
Vector3 leftDownUp = upCorner - leftDownCorner;
Vector3 upRightDown = rightDownCorner - upCorner;
Vector3 rightDownLeftDown = leftDownCorner - rightDownCorner;
uint subdiv = 3 * i;
for (uint s = 1; s < subdiv; s++)
{
Vector3 leftDownUpSubdiv = leftDownCorner + leftDownUp * (float)s / (float)subdiv;
AttemptAdding (leftDownUpSubdiv, center, distanceCutoffSquared, outPositions);
Vector3 upRightDownSubdiv = upCorner + upRightDown * (float)s / (float)subdiv;
AttemptAdding (upRightDownSubdiv, center, distanceCutoffSquared, outPositions);
Vector3 rightDownLeftDownSubdiv = rightDownCorner + rightDownLeftDown * (float)s / (float)subdiv;
AttemptAdding (rightDownLeftDownSubdiv, center, distanceCutoffSquared, outPositions);
}
}
}
}
}
void GenerateRing (TriangleProps props, float radius, float innerRadius, float height, uint levels, List<Vector3> outPositions)
{
float chordLength = props.side;
float angle = Mathf.Clamp (2.0f * Mathf.Asin (chordLength / (2.0f * radius)), 0.01f, 2.0f * Mathf.PI);
uint slicesAtRadius = (uint)Mathf.FloorToInt (2.0f * Mathf.PI / angle);
uint layers = (uint)Mathf.Max (Mathf.Ceil ((radius - innerRadius) / props.height), 0.0f);
for (uint level = 0; level < levels; level++)
{
float tLevel = levels == 1 ? 0 : (float)level / (float)(levels - 1);
float y = height * tLevel;
float iterationOffset0 = level % 2 == 0 ? 0.0f : 0.5f;
for (uint layer = 0; layer < layers; layer++)
{
float tLayer = layers == 1 ? 1.0f : (float)layer / (float)(layers - 1);
float tIterations = (tLayer * (radius - innerRadius) + innerRadius - kMinInnerRadius) / (radius - kMinInnerRadius);
uint slices = (uint)Mathf.CeilToInt (Mathf.Lerp (kMinIterations, slicesAtRadius, tIterations));
float x = innerRadius + (radius - innerRadius) * tLayer;
Vector3 position = new Vector3 (x, y, 0.0f);
float layerSliceOffset = layer % 2 == 0 ? 0.0f : 0.5f;
for (uint slice = 0; slice < slices; slice++)
{
Quaternion rotation = Quaternion.Euler (0.0f, (slice + iterationOffset0 + layerSliceOffset) * 360.0f / (float)slices, 0.0f);
outPositions.Add (rotation * position);
}
}
}
}
}
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