Hi i seem to be having a positional light problem when it is hitting the surface of my ground. I have created a texture loader and then used that to create a heightmap which looks greate when using a directional light but for some reason when i use this positional light i get a jagged edge to it between the light and dark areas(this is more clear in the screen shot below). Any ideas please?
screen shot
http://img291.imageshack.us/my.php?image=screemshotbv4.jpg
Here's where i set up my light
//init
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_NORMALIZE);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
GLfloat lightPosition2[] = {0,0,0,1};
GLfloat spot_direction[] = {0,0,1};
glLightf(GL_LIGHT1, GL_SPOT_CUTOFF, 35.0);
glLightfv(GL_LIGHT1, GL_SPOT_DIRECTION, spot_direction);
glLightf(GL_LIGHT1, GL_CONSTANT_ATTENUATION, 0.5);
glLightf(GL_LIGHT1, GL_LINEAR_ATTENUATION, 0.0);
glLightf(GL_LIGHT1, GL_QUADRATIC_ATTENUATION, 0.0);
glLightfv(GL_LIGHT1, GL_AMBIENT, ambientLight2);
glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuseLight2);
glLightfv(GL_LIGHT1, GL_SPECULAR, specularLight2);
glLightfv(GL_LIGHT1, GL_POSITION, lightPosition2);
glEnable(GL_LIGHT1);
Heres where i create the normals for my ground, which basically collect all the vertex around the current and then takes a weighted average of them.
for(int z = 0; z < length; z++)
{
for(int x = 0; x < width; x++)
{
Vec sum(0.0f, 0.0f, 0.0f);
Vec back;
//Collects vectors around current
if (z > 0) //Checks to see if its on the edge
{
back = Vec(0.0f, hs[z - 1][x] - hs[z][x], -1.0f);
}
Vec front;
if (z < length - 1) //Checks to see if its on the edge
{
front = Vec(0.0f, hs[z + 1][x] - hs[z][x], 1.0f);
}
Vec left;
if (x > 0) //Checks to see if its on the edge
{
left = Vec(-1.0f, hs[z][x - 1] - hs[z][x], 0.0f);
}
Vec right;
if (x < width - 1) //Checks to see if its on the edge
{
right = Vec(1.0f, hs[z][x + 1] - hs[z][x], 0.0f);
}
//Takes cross product of vectors
if (x > 0 && z > 0)
{
sum += back.cross(left);
}
if (x > 0 && z < length - 1)
{
sum += left.cross(front);
}
if (x < width - 1 && z < length - 1)
{
sum += front.cross(right);
}
if (x < width - 1 && z > 0)
{
sum += right.cross(back);
}
//Places vectors into normals array
normals[z][x] = sum;
}
}
Many Thanks
