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## 6 posts in this topic

Hello, I have somehow built a model (partial) which looks like a stadium. I have attached the picture for your kind perusal. The field ground has been textured. Now for a particular position, my model looks too much lighted as you can see the far half of the seats look totally white. I am a bit new in modeling lighting. If I don't consider the specular parameter, my model looks dull and seats are not properly outlined. So I added some specular component of light and shininess to the model. But the far half of the model looks too much lighted. I found textured portion is unaffected by lighting. Could any one explain why?
Could any one suggest how can I adjust the lighting parameters so that model does not look too shiny and seats around the field are also properly outlined.

I am using simple OpenGL, no GLSL.

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Show us the relevant code you're using so we can see your configuration. Edited by GeneralQuery
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void initGL(){

static const GLfloat light_model_ambient[] = {1.0f, 1.0f, 1.0f, 1.0f};

glLightModelfv(GL_LIGHT_MODEL_AMBIENT, light_model_ambient);

glEnable(GL_DEPTH_TEST);

float diffuse[]  = {1.0f, 1.0f, 1.0f, 1.0f};
float position[] = {5.0f, 5.0f, 5.0f, 1.0f};
float specular[] = {1.0f, 1.0f, 1.0f, 1.0f};

glEnable(GL_LIGHTING);
glEnable( GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_DIFFUSE,  diffuse);
glLightfv(GL_LIGHT0, GL_POSITION, position);
glLightfv(GL_LIGHT0, GL_SPECULAR, specular);

glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

float shininess = 5.0f;
glEnable(GL_COLOR_MATERIAL);
glMaterialf( GL_FRONT_AND_BACK, GL_SHININESS, shininess);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR,  specular);

}

void drawSceneGraphics()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

//Render the checked floor.
glEnable(GL_BLEND);
glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
renderAll();

glDisable(GL_BLEND);
}


void renderAll(){

glPushMatrix();

//Render the middle textured field

glEnable(GL_TEXTURE_2D);
renderField(size);
glDisable(GL_TEXTURE_2D);
glPopMatrix();

// Render track 1 (red color)

glPushMatrix();
renderTexturedTrack_1(size);
glPopMatrix();

// Render Track 2 (blue color)

glPushMatrix();
renderTexturedTrack_2(size);
glPopMatrix();

// Render seats

glPushMatrix();
drawModel();
glPopMatrix();

return;
}


Thanks in advance to all.
void glutReshape(int width, int height)
{

static const double kPI = 3.1415926535897932384626433832795;
static const double kFovY = 45;

double nearDist, farDist, aspect;

width =  glutGet(GLUT_WINDOW_WIDTH);
height = glutGet(GLUT_WINDOW_HEIGHT);

if (width && height)
{
glViewport(0, 0, width, height);

// Compute the viewing parameters based on a fixed fov and viewing
// a canonical box centered at the origin.

nearDist = 15.0 / tan((kFovY / 2.0) * kPI / 180.0);
farDist = nearDist + 70.0;
aspect = (double) width / height;

glMatrixMode(GL_PROJECTION);
gluPerspective(kFovY, aspect, 0.1, 140);

// Place the camera down the Z axis looking at the origin.

glMatrixMode(GL_MODELVIEW);

gluLookAt(0, 25.0, nearDist + 35.0, 0, 0.0, 0, 0, 1, 0.0);

}
}



I have attached some part of my code. Please provide me some suggestions so that I can fix the lighting parameters.

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Your lighting terms don't look right. From a brief skim of your code:

Why is the ambient term at full intensity? It shouldn't be otherwise you have no dynamic range to work with (hence the washed out lighting). Try a lower value like 0.2f.

Your specular shininess is very broad. A low number such as the one you are using will wash out a lot of your model, especially with vertex lighting (which you are using). Try a higher value like 64.0f or 128.0f.

Your specular term is very bright. This may be contributing to your problem so try a lower value like 0.8f.
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Hi, thank you very much for taking time to answer my question. As per your suggestion I have changed the lighting parameters as follows:

The attached picture is for a shininess value of 128.0f. Setting the value at 64.0f does not make much difference in output.

void initGL()
{
static const GLfloat light_model_ambient[] = {0.2f, 0.2f, 0.2f, 1.0f};

glLightModelfv(GL_LIGHT_MODEL_AMBIENT, light_model_ambient);

glEnable(GL_DEPTH_TEST);

float diffuse[]  = {1.0f, 1.0f, 1.0f, 1.0f};
float position[] = {5.0f, 5.0f, 5.0f, 1.0f};
float specular[] = {0.8f, 0.8f, 0.8f, 1.0f};

glEnable(GL_LIGHTING);
glEnable( GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_DIFFUSE,  diffuse);
glLightfv(GL_LIGHT0, GL_POSITION, position);
glLightfv(GL_LIGHT0, GL_SPECULAR, specular);

glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

float shininess = 128.0f;
glEnable(GL_COLOR_MATERIAL);
glMaterialf( GL_FRONT_AND_BACK, GL_SHININESS, shininess);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR,  specular);

}


Could you suggest me what is going wrong with my code.

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I have been able to get better output by adding the following:

glEnable(GL_NORMALIZE);

Thank you for sharing ideas. But I have one question why textured portion remains unaffected by lighting?

Thanks again.

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You probably have the textures set to decal instead of modulate.

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