Android Open Source - android-per-pixel-lighting-demo Triangle

• Back to OpenGL/Demo  ↑

From Project

Back to project page android-per-pixel-lighting-demo.

License

The source code is released under:

Apache License

Java Source Code

package com.pedroedrasousa.object3d;
//w  ww .j av a  2  s .co m
import com.pedroedrasousa.engine.Vec2;
import com.pedroedrasousa.engine.Vec3;

public class Triangle {
  
  // Vertex coordinates (x, y, z)
  private Vec3 mVertex1;
  private Vec3 mVertex2;
  private Vec3 mVertex3;
  
  // Texture coordinates (s, t)
  private Vec2 mTexCoords1;
  private Vec2 mTexCoords2;
  private Vec2 mTexCoords3;
  
  // Triangle tangent space
  private Vec3 mNormal;
  private Vec3 mTangent;
  private Vec3 mBinormal;
  
  private String mSmoothGroup;

  // Calculate triangle normal, tangent and binormal.
  public void calcTangentSpace() {

    Vec3 v21 = Vec3.sub(mVertex2, mVertex1);    // v2 -> v1 vector
    Vec3 v31 = Vec3.sub(mVertex3, mVertex1);    // v3 -> v1 vector

    Vec2 st21 = Vec2.sub(mTexCoords2, mTexCoords1);  // st2 -> st1 vector
    Vec2 st31 = Vec2.sub(mTexCoords3, mTexCoords1);  // st3 -> st1 vector
    
    // Normal can be found by calculating the cross product between v21 and v31.
    mNormal = Vec3.cross(v21, v31);
    
    float r = st21.x * st31.y - st31.x * st21.y;
    r = (r == 0) ? 1 : 1 / r;
    
    // sdir = (v21 * st31.y - v31, st21.y) * r
    Vec3 sdir = Vec3.sub(Vec3.mul(v21, st31.y), Vec3.mul(v31, st21.y));
    sdir.scale(r);
    
    // tdir = (v21 * st31.x - v31, st21.x) * r
    Vec3 tdir = Vec3.sub( Vec3.mul(v21, st31.x), Vec3.mul(v31, st21.x));
    tdir.scale(r);
    
    // Gram-Schmidt orthogonalize
    mTangent = Vec3.sub(sdir, Vec3.mul(mNormal, Vec3.dot(mNormal, sdir)));
    mTangent.normalize();
    
    // Binormal can be found by calculating the cross product between the normal and tangent.
    mBinormal = Vec3.cross(mNormal, mTangent);

    // Binormal must have the same orientation than tdir, check whether it must be inverted or not.
    if (Vec3.dot(mBinormal, tdir) < 0.0f) {
      // Binormal has the wrong direction. Invert it.
      mBinormal.scale(-1.0f);
    }
  }
  
  // Getters and setters
  
  public Vec3 getVertexCoord1() { return mVertex1; }
  public Vec3 getVertexCoord2() { return mVertex2; }
  public Vec3 getVertexCoord3() { return mVertex3; }
  
  public void setVertexCoord1(Vec3 vertexCoord) { mVertex1 = vertexCoord; }
  public void setVertexCoord2(Vec3 vertexCoord) { mVertex2 = vertexCoord; }
  public void setVertexCoord3(Vec3 vertexCoord) { mVertex3 = vertexCoord; }  
  public void setVertexCoord(Vec3 v1, Vec3 v2, Vec3 v3) { mVertex1 = v1; mVertex2 = v2; mVertex3 = v3; }
  
  public Vec2 getTexCoord1() { return mTexCoords1; }
  public Vec2 getTexCoord2() { return mTexCoords2; }
  public Vec2 getTexCoord3() { return mTexCoords3; }
  
  public void setTexCoord1(Vec2 texCoord) { mTexCoords1 = texCoord; }
  public void setTexCoord2(Vec2 texCoord) { mTexCoords2 = texCoord; }
  public void setTexCoord3(Vec2 texCoord) { mTexCoords3 = texCoord; }
  public void setTexCoord(Vec2 uv1, Vec2 uv2, Vec2 uv3) { mTexCoords1 = uv1; mTexCoords2 = uv2; mTexCoords3 = uv3; }
  
  public Vec3 getNormal()    { return mNormal; }
  public Vec3 getTangent()  { return mTangent; }
  public Vec3 getBinormal()  { return mBinormal; }
  
  public void setNormal(Vec3 normal)    { mNormal  = normal; }
  public void setTangent(Vec3 tangent)  { mTangent  = tangent;}
  public void setBinormal(Vec3 binormal)  { mBinormal  = binormal; }
  
  public String getSmoothGroup() { return mSmoothGroup; }
  public void setSmoothGroup(String smoothGroup) { mSmoothGroup = smoothGroup; }
}

Java Source Code List

• Back to OpenGL/Demo  ↑