Nice looking lines [OpenGL]

[User137]

Like this site said:
http://www.allegro.cc/forums/thread/592220
It looks like this http://i35.tinypic.com/1zcfleb.png

And a quad with texture (also shown in next screenshot only scaled up from 4x4 used in test). This line does also scale well and remain smooth, as it is loaded with GL_LINEAR filter.
Looks like http://i38.tinypic.com/fjoler.png

[arthurprs]

thanks

[arthurprs]

i'm having some problems here,

zoomed texture, the original is 4x4px



and how it looks when i draw stretched


filters used:
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

[waran]

And where is your Problem?

It does what it says - it filters GL_LINEAR. Means in this case a
smooth line from black to white to black.

If you want a hard cut you should use GL_NEAREST.

[arthurprs]

And where is your Problem?

It does what it says - it filters GL_LINEAR. Means in this case a
smooth line from black to white to black.

If you want a hard cut you should use GL_NEAREST.

look the results of user137, and he used GL_LINEAR



GL_NEAREST really solved the problem

[JSoftware]

Try clamp_to_edge or clamp as wrap mode

[User137]

If you use GL_NEAREST you lose all the details from the texture itself and effects you can achieve with it.

It's in your texture coordinates. I didn't use full area of the texture but a slice through the middle, that way the end points don't go as smooth. To make end points smooth requires quads also to the end points.

This would be the exact same to use a 1 dimensional texture 4x1 0,255,255,0 but my engine isn't supporting them yet.

This is the exact code used, not very optimal but works...:
[pascal]glLoadIdentity;
glTranslatef(0,0,-5);
glSetTex(dotTex);
glTranslatef(-2,-1,0);
glRotatef(angle(-2,-1,2,1),0,0,1);
d:=hypot(4,2);
glScalef(d,d,1);
d:=0.01;
glBegin(GL_QUADS);
glColor3f(1,0.5,0.2);
glTexCoord2f(0.0,0.5); glVertex2f(0, d);
glTexCoord2f(1.0,0.5); glVertex2f(0, -d);
glTexCoord2f(1.0,0.5); glVertex2f(1, -d);
glTexCoord2f(0.0,0.5); glVertex2f(1, d);
glEnd;[/pascal]

When i render that with d:=0.1 i get these (added together with msPaint):

[arthurprs]

i'm trying something more simple (not rotated), but i could not get that "gradient effect" on the sides of the line

[pascal] glBegin(GL_QUADS);
glTexCoord2f(0.0, 0.5); glVertex2f(100, 4);
glTexCoord2f(1.0, 0.5); glVertex2f(300, 4);
glTexCoord2f(1.0, 0.5); glVertex2f(300, 14);
glTexCoord2f(0.0, 0.5); glVertex2f(100, 14);
glEnd();[/pascal]

[User137]

Maybe this?
[pascal] glBegin(GL_QUADS);
glTexCoord2f(0.0, 0.5); glVertex2f(100, 14);
glTexCoord2f(1.0, 0.5); glVertex2f(100, 4);
glTexCoord2f(1.0, 0.5); glVertex2f(300, 4);
glTexCoord2f(0.0, 0.5); glVertex2f(300, 14);
glEnd();[/pascal]

[arthurprs]

Maybe this?
[pascal] glBegin(GL_QUADS);
glTexCoord2f(0.0, 0.5); glVertex2f(100, 14);
glTexCoord2f(1.0, 0.5); glVertex2f(100, 4);
glTexCoord2f(1.0, 0.5); glVertex2f(300, 4);
glTexCoord2f(0.0, 0.5); glVertex2f(300, 14);
glEnd();[/pascal]

same :\

zoomed texture, the original is 4x4px


mag and min filters set to GL_LINEAR