OpenGL 灯不工作

Question

我正在使用此代码使用 LWJGL 绘制具有不同颜色的不同立方体：

    GL11.glBegin(GL11.GL_QUADS);
        GL11.glColor3f(rcol.x, rcol.y, rcol.z); // Color Vector
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);         // Top Right Of The Quad (Top)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);         // Top Left Of The Quad (Top)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);         // Bottom Left Of The Quad (Top)
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);             // Bottom Right Of The Quad (Top)

        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y - rsiz.y, rpos.z + rsiz.z);         // Top Right Of The Quad (Bottom)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y - rsiz.y, rpos.z + rsiz.z);         // Top Left Of The Quad (Bottom)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y - rsiz.y, rpos.z - rsiz.z);         // Bottom Left Of The Quad (Bottom)
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y - rsiz.y, rpos.z - rsiz.z);         // Bottom Right Of The Quad (Bottom)

        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);         // Top Right Of The Quad (Front)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);         // Top Left Of The Quad (Front)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y - rsiz.y, rpos.z + rsiz.z);         // Bottom Left Of The Quad (Front)
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y - rsiz.y, rpos.z + rsiz.z);         // Bottom Right Of The Quad (Front)

        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y - rsiz.y, rpos.z - rsiz.z);         // Bottom Left Of The Quad (Back)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y - rsiz.y, rpos.z - rsiz.z);         // Bottom Right Of The Quad (Back)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);         // Top Right Of The Quad (Back)
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);         // Top Left Of The Quad (Back)

        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);         // Top Right Of The Quad (Left)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);     // Top Left Of The Quad (Left)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y - rsiz.y, rpos.z - rsiz.z);         // Bottom Left Of The Quad (Left)
        GL11.glVertex3f(rpos.x - rsiz.x, rpos.y - rsiz.y, rpos.z + rsiz.z);         // Bottom Right Of The Quad (Left)

        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);         // Top Right Of The Quad (Right)
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);         // Top Left Of The Quad (Right)
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y - rsiz.y, rpos.z + rsiz.z);         // Bottom Left Of The Quad (Right)
        GL11.glVertex3f(rpos.x + rsiz.x, rpos.y - rsiz.y, rpos.z - rsiz.z);         // Bottom Right Of The Quad (Right)
    GL11.glEnd();

它把立方体画得很好，颜色也很完美，但只要我给它加光，一切都会变白，看起来很糟糕。这是我的照明代码：

GL11.glEnable(GL11.GL_LIGHTING);
GL11.glEnable(GL11.GL_LIGHT0);

float lightAmbient[] = { 0.5f, 0.5f, 0.5f, 1.0f };  // Ambient Light Values
float lightDiffuse[] = { 1.0f, 1.0f, 1.0f, 1.0f };      // Diffuse Light Values
float lightPosition[] = { 20.0f, 15.0f, 20.0f, 1.0f }; // Light Position
float lightSpecular[] = { 1.0f, 1.0f, 1.0f, 1.0f }; // Light Position

ByteBuffer temp = ByteBuffer.allocateDirect(16);
temp.order(ByteOrder.nativeOrder())
GL11.glLight(GL11.GL_LIGHT0, GL11.GL_SPECULAR, (FloatBuffer)temp.asFloatBuffer().put(lightSpecular).flip());   
GL11.glLight(GL11.GL_LIGHT0, GL11.GL_AMBIENT, (FloatBuffer)temp.asFloatBuffer().put(lightAmbient).flip());              // Setup The Ambient Light
GL11.glLight(GL11.GL_LIGHT0, GL11.GL_DIFFUSE, (FloatBuffer)temp.asFloatBuffer().put(lightDiffuse).flip());              // Setup The Diffuse Light
GL11.glLight(GL11.GL_LIGHT0, GL11.GL_POSITION,(FloatBuffer)temp.asFloatBuffer().put(lightPosition).flip());         // Position The Light

有谁知道我在这里做错了什么？这是示例图片：

Answer 1

您需要使用glNormal3f 为您的四边形定义normal vector。法线向量用于光照计算。

法线向量垂直于您的表面。因此，例如，对于您的第一个四边形：

GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);         // Top Right Of The Quad (Top)
GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z - rsiz.z);         // Top Left Of The Quad (Top)
GL11.glVertex3f(rpos.x - rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);         // Bottom Left Of The Quad (Top)
GL11.glVertex3f(rpos.x + rsiz.x, rpos.y + rsiz.y, rpos.z + rsiz.z);             // Bottom Right Of The Quad (Top)

y 坐标是恒定的，因此垂直于该表面的法向量可以
是(0, 1, 0) 或(0, -1, 0)。