OpenGL法線誤解？

我想讓我的燈光在OpenGL中工作，使用LWJGL作爲實現庫。我認爲我遇到的問題是我沒有正確設置法線，因此照明在某些角度不起作用。下面是我測試立方體代碼：OpenGL法線誤解？

glBegin(GL_QUADS); 

glColor3f(r,g,b); 

glNormal3f(position.x, position.y, position.z - radius - 0.1f); 
glVertex3f(position.x + radius, position.y + radius, position.z - radius); 
glVertex3f(position.x + radius, position.y - radius, position.z - radius); 
glVertex3f(position.x - radius, position.y - radius, position.z - radius); 
glVertex3f(position.x - radius, position.y + radius, position.z - radius); 

glNormal3f(position.x, position.y, position.z + radius + 0.1f); 
glVertex3f(position.x + radius, position.y + radius, position.z + radius); 
glVertex3f(position.x + radius, position.y - radius, position.z + radius); 
glVertex3f(position.x - radius, position.y - radius, position.z + radius); 
glVertex3f(position.x - radius, position.y + radius, position.z + radius); 

glNormal3f(position.x - radius - 0.1f, position.y, position.z); 
glVertex3f(position.x - radius, position.y + radius, position.z + radius); 
glVertex3f(position.x - radius, position.y - radius, position.z + radius); 
glVertex3f(position.x - radius, position.y - radius, position.z - radius); 
glVertex3f(position.x - radius, position.y + radius, position.z - radius); 

glNormal3f(position.x + radius + 0.1f, position.y, position.z); 
glVertex3f(position.x + radius, position.y + radius, position.z + radius); 
glVertex3f(position.x + radius, position.y - radius, position.z + radius); 
glVertex3f(position.x + radius, position.y - radius, position.z - radius); 
glVertex3f(position.x + radius, position.y + radius, position.z - radius); 

glNormal3f(position.x, position.y - radius - 0.1f, position.z); 
glVertex3f(position.x + radius, position.y - radius, position.z + radius); 
glVertex3f(position.x - radius, position.y - radius, position.z + radius); 
glVertex3f(position.x - radius, position.y - radius, position.z - radius); 
glVertex3f(position.x + radius, position.y - radius, position.z - radius); 

glNormal3f(position.x, position.y + radius + 0.1f, position.z); 
glVertex3f(position.x + radius, position.y + radius, position.z + radius); 
glVertex3f(position.x - radius, position.y + radius, position.z + radius); 
glVertex3f(position.x - radius, position.y + radius, position.z - radius); 
glVertex3f(position.x + radius, position.y + radius, position.z - radius); 

glEnd();

來源

2013-03-09 Philippe Paré

所以......這是什麼* *咋辦做的，什麼是它實際上做什麼？ – 2013-03-09 21:53:59

我只是想確定我的法線是正確的，因爲我不是很明白如何計算它們......這是表面前的一個點？對？ – 2013-03-09 21:55:35

@PhilippeParé：不，它不是表面前的點，而是垂直於表面的方向，用長度爲1的矢量表示。可以使用跨越三角形的矢量的叉積在R 3中計算它們。 – datenwolf 2013-03-09 21:59:14

法向量相對於頂點本身，總是歸一化（即：他們有一個長度）。

所以，像這樣的一行：

glNormal3f(position.x, position.y, position.z - radius - 0.1f);

應改爲：

glNormal3f(0.0f, 0.0f, 1.0f);

來源

2013-03-09 21:54:45

OpenGL法線誤解？

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