照明和OpenGL ES [英] Lighting and OpenGL ES
问题描述
我正在努力在OpenGL ES iPhone场景上获得简单的照明.我正在显示一个以原点为中心的简单对象，并使用Arcball通过触摸屏幕来旋转它.所有这些都很好用，除了我尝试添加一个固定的光源(眼睛位置固定)并且拧得很烂:整个对象(在此示例中为二十面体)均被均匀照明，即，它们都以相同的颜色显示.
我已尽可能简化了代码，因此它是独立的，仍然可以再现我的经验:
glClearColor (0.25, 0.25, 0.25, 1.);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable (GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrthof(-1, 1, -(float)backingWidth/backingHeight, (float)backingWidth/backingHeight, -10, 10);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
GLfloat ambientLight[] = { 0.2f, 0.2f, 0.2f, 1.0f };
GLfloat diffuseLight[] = { 0.8f, 0.8f, 0.8, 1.0f };
GLfloat specularLight[] = { 0.5f, 0.5f, 0.5f, 1.0f };
GLfloat position[] = { -1.5f, 1.0f, -400.0f, 0.0f };
glEnable(GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight);
glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLight);
glLightfv(GL_LIGHT0, GL_SPECULAR, specularLight);
glLightfv(GL_LIGHT0, GL_POSITION, position);
glShadeModel(GL_SMOOTH);
glEnable(GL_NORMALIZE);
float currRot[4];
[arcball getCurrentRotation:currRot];
glRotatef (currRot[0], currRot[1], currRot[2], currRot[3]);
float f[4];
f[0] = 0.5; f[1] = 0; f[2] = 0; f[3] = 1;
glMaterialfv (GL_FRONT_AND_BACK, GL_AMBIENT, f);
glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, f);
f[0] = 0.2; f[1] = 0.2; f[2] = 0.2; f[3] = 1;
glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, f);
glEnableClientState (GL_VERTEX_ARRAY);
drawSphere(0, 0, 0, 1);
drawSphere函数实际上绘制了二十面体:
static void drawSphere (float x, float y, float z, float rad)
{
glPushMatrix ();
glTranslatef (x, y, z);
glScalef (rad, rad, rad);
// Icosahedron
const float vertices[] =
{ 0., 0., -1., 0., 0., 1., -0.894427, 0., -0.447214, 0.894427, 0.,
0.447214, 0.723607, -0.525731, -0.447214, 0.723607, 0.525731,
-0.447214, -0.723607, -0.525731, 0.447214, -0.723607, 0.525731,
0.447214, -0.276393, -0.850651, -0.447214, -0.276393, 0.850651,
-0.447214, 0.276393, -0.850651, 0.447214, 0.276393, 0.850651,
0.447214 };
const GLubyte indices[] =
{ 1, 11, 7, 1, 7, 6, 1, 6, 10, 1, 10, 3, 1, 3, 11, 4, 8, 0, 5, 4, 0,
9, 5, 0, 2, 9, 0, 8, 2, 0, 11, 9, 7, 7, 2, 6, 6, 8, 10, 10, 4, 3,
3, 5, 11, 4, 10, 8, 5, 3, 4, 9, 11, 5, 2, 7, 9, 8, 6, 2 };
glVertexPointer (3, GL_FLOAT, 0, vertices);
glDrawElements (GL_TRIANGLES, sizeof(indices)/sizeof(indices[0]), GL_UNSIGNED_BYTE, indices);
glPopMatrix ();
}
我看到的电影结果是此处.感谢任何可以阐明这一点的人(不要开玩笑！).我敢肯定，对于某人来说，它看起来非常微不足道，但是我发誓，在此之前，我已经看过许多照明教程，并且陷入困境.
尝试使用默认普通适用于一切.
I'm working on getting a simple lighting right on my OpenGL ES iPhone scene. I'm displaying a simple object centered on the origin, and using an arcball to rotate it by touching the screen. All this works nicely, except I try to add one fixed light (fixed w.r.t. eye position) and it is badly screwed: the whole object (an icosahedron in this example) is lit uniformly, i.e. it all appears in the same color.
I have simplified my code as much as possible so it's standalone and still reproduces what I experience:
glClearColor (0.25, 0.25, 0.25, 1.);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable (GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrthof(-1, 1, -(float)backingWidth/backingHeight, (float)backingWidth/backingHeight, -10, 10);
glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
GLfloat ambientLight[] = { 0.2f, 0.2f, 0.2f, 1.0f };
GLfloat diffuseLight[] = { 0.8f, 0.8f, 0.8, 1.0f };
GLfloat specularLight[] = { 0.5f, 0.5f, 0.5f, 1.0f };
GLfloat position[] = { -1.5f, 1.0f, -400.0f, 0.0f };
glEnable(GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight);
glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLight);
glLightfv(GL_LIGHT0, GL_SPECULAR, specularLight);
glLightfv(GL_LIGHT0, GL_POSITION, position);
glShadeModel(GL_SMOOTH);
glEnable(GL_NORMALIZE);
float currRot[4];
[arcball getCurrentRotation:currRot];
glRotatef (currRot[0], currRot[1], currRot[2], currRot[3]);
float f[4];
f[0] = 0.5; f[1] = 0; f[2] = 0; f[3] = 1;
glMaterialfv (GL_FRONT_AND_BACK, GL_AMBIENT, f);
glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, f);
f[0] = 0.2; f[1] = 0.2; f[2] = 0.2; f[3] = 1;
glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, f);
glEnableClientState (GL_VERTEX_ARRAY);
drawSphere(0, 0, 0, 1);
where the drawSphere function actually draws an icosahedron:
static void drawSphere (float x, float y, float z, float rad)
{
glPushMatrix ();
glTranslatef (x, y, z);
glScalef (rad, rad, rad);
// Icosahedron
const float vertices[] =
{ 0., 0., -1., 0., 0., 1., -0.894427, 0., -0.447214, 0.894427, 0.,
0.447214, 0.723607, -0.525731, -0.447214, 0.723607, 0.525731,
-0.447214, -0.723607, -0.525731, 0.447214, -0.723607, 0.525731,
0.447214, -0.276393, -0.850651, -0.447214, -0.276393, 0.850651,
-0.447214, 0.276393, -0.850651, 0.447214, 0.276393, 0.850651,
0.447214 };
const GLubyte indices[] =
{ 1, 11, 7, 1, 7, 6, 1, 6, 10, 1, 10, 3, 1, 3, 11, 4, 8, 0, 5, 4, 0,
9, 5, 0, 2, 9, 0, 8, 2, 0, 11, 9, 7, 7, 2, 6, 6, 8, 10, 10, 4, 3,
3, 5, 11, 4, 10, 8, 5, 3, 4, 9, 11, 5, 2, 7, 9, 8, 6, 2 };
glVertexPointer (3, GL_FLOAT, 0, vertices);
glDrawElements (GL_TRIANGLES, sizeof(indices)/sizeof(indices[0]), GL_UNSIGNED_BYTE, indices);
glPopMatrix ();
}
A movie of what I see as the result is here. Thanks to anyone who can shed some light into this (no kidding!). I'm sure it will look embarassingly trivial to someone, but I swear I have looked at many lighting tutorials before this and am stuck.
Try adding some vertex normals using glNormalPointer(). It looks like OpenGL ES is just using the default normal for everything.
这篇关于照明和OpenGL ES的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
