From bd2d3801ef7aef621b8cdc482dd02732cf7d1a14 Mon Sep 17 00:00:00 2001
From: tengge1 <930372551@qq.com>
Date: Thu, 14 Mar 2019 19:48:51 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E7=9D=80=E8=89=B2=E5=99=A8?=
 =?UTF-8?q?=E4=BB=A3=E7=A0=81=E3=80=82?=
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---
 ShadowEditor.Web/src/shader/ShaderChunk.js     |  5 +++++
 ShadowEditor.Web/src/shader/vec3/angleTo.glsl  | 11 +++++++++++
 ShadowEditor.Web/src/shader/vec3/lengthSq.glsl |  6 ++++++
 3 files changed, 22 insertions(+)
 create mode 100644 ShadowEditor.Web/src/shader/vec3/angleTo.glsl
 create mode 100644 ShadowEditor.Web/src/shader/vec3/lengthSq.glsl

diff --git a/ShadowEditor.Web/src/shader/ShaderChunk.js b/ShadowEditor.Web/src/shader/ShaderChunk.js
index d6a29206..3463c9d3 100644
--- a/ShadowEditor.Web/src/shader/ShaderChunk.js
+++ b/ShadowEditor.Web/src/shader/ShaderChunk.js
@@ -1,4 +1,7 @@
 import applyMatrix4 from './vec3/applyMatrix4.glsl';
+import lengthSq from './vec3/lengthSq.glsl';
+import angleTo from './vec3/angleTo.glsl';
+
 import makeOrthographic from './mat4/makeOrthographic.glsl';
 import makePerspective from './mat4/makePerspective.glsl';
 import makePerspective2 from './mat4/makePerspective2.glsl';
@@ -9,6 +12,8 @@ import decomposeMatrix from './mat4/decomposeMatrix.glsl';
 Object.assign(THREE.ShaderChunk, {
     // vec3
     applyMatrix4: applyMatrix4,
+    lengthSq: lengthSq,
+    angleTo: angleTo,
 
     // mat4
     makeOrthographic: makeOrthographic,
diff --git a/ShadowEditor.Web/src/shader/vec3/angleTo.glsl b/ShadowEditor.Web/src/shader/vec3/angleTo.glsl
new file mode 100644
index 00000000..a714348e
--- /dev/null
+++ b/ShadowEditor.Web/src/shader/vec3/angleTo.glsl
@@ -0,0 +1,11 @@
+#include <lengthSq>
+
+/**
+ * 求两个向量之间的夹角
+ */
+float angleTo(vec3 v1, vec3 v2) {
+    float theta = dot(v1, v2) / sqrt(lengthSq(v1) * lengthSq(v2) );
+    
+    // clamp, to handle numerical problems
+    return acos(clamp(theta, -1.0, 1.0));
+}
\ No newline at end of file
diff --git a/ShadowEditor.Web/src/shader/vec3/lengthSq.glsl b/ShadowEditor.Web/src/shader/vec3/lengthSq.glsl
new file mode 100644
index 00000000..f8e9a727
--- /dev/null
+++ b/ShadowEditor.Web/src/shader/vec3/lengthSq.glsl
@@ -0,0 +1,6 @@
+/**
+ * 计算vec3长度的平方
+ */
+float lengthSq(vec3 v) {
+    return v.x * v.x + v.y * v.y + v.z * v.z;
+}
\ No newline at end of file