Comments for The graphics blog

Comment on Screenshots by NaliPL

NaliPL — Tue, 07 Feb 2012 00:15:24 +0000

reinterpret_cast
change to reinterpret_cast

require include :
#include
#include

if not using “using namespace std;

Then place std before; std::fstream std::ios

Comment on Budda brot style fractals by Peter Wallström

Peter Wallström — Mon, 26 Dec 2011 21:40:08 +0000

I use a pretty simple setup,i basically just feed random points into a vertex buffer and then render them as points, then instead of using the fragment shader to render the mandelbrot (and similar) fractals as i normally do, i use the geometry shader , but instead of counting how long each point it takes to escape i just simply plot the escape path with points, after some creative tonemapping and a lot of time i get the final result.
But it is a pretty chaotic system that relies on a scattering effect so i doubt that it will ever get a real time approximation (or faster for that matter), unless you start using stuff like quantum computing processors, either way that math is far beyond anything we have today.

Comment on Budda brot style fractals by Henrik Nordvik

Henrik Nordvik — Mon, 26 Dec 2011 20:58:27 +0000

How did you make it? It is beautiful. I wonder if it would be possible to make a real-time approximation of this.

Comment on Screenshots by Peter Wallström

Peter Wallström — Sat, 10 Dec 2011 11:47:54 +0000

Tanks, and pretty soon i will release an even better version in my toolkit that can deal with compression

Comment on Screenshots by yifan

yifan — Sat, 10 Dec 2011 05:52:00 +0000

very nice function. I use it to save my ray tracing picture.

Comment on PCF by Peter Wallström

Peter Wallström — Sun, 28 Aug 2011 21:15:48 +0000

yea, your right, tanks for catching that.
Though in reality just using a regular array like this is a bit pointless, to get a better result you should really use a small array of random coordinates that changes for each screen coordinate.
I guess i have to add it to the list of new tutorials to write, im up to like 9 so far and some of them are multiparters.

Comment on PCF by Barotto

Barotto — Sun, 28 Aug 2011 21:00:02 +0000

thanks for the tutorial.

there’s a little bug in the shader code: blur_spread is a 5 elements array, so it should be x<5 (or x<=4) and not x<4. the same goes for the inner y.

Comment on Geometry shaders part 3 by Peter Wallström

Peter Wallström — Sat, 11 Jun 2011 14:07:56 +0000

Dragon curve version of the shader, because it only produces two lines for each incoming line you need to change the code from kochsize*=4; to kochsize*=2; in the transform function.
it also works well if you render it with up to 6 million lines instead of 6000 as you get a nice highly detailed filled fractal.

#version 150

in vec4 pos[];

void main( void )
{

vec3 vin=vec3(0.0,0.0,1.0); //vector pointing in

vec3 v1=(pos[1].xyz-pos[0].xyz)/2.0; //vector pointing half the way to pos[1]
vec3 v2=cross(vin,normalize(v1)); // vector perpendicular to v1
float mag=length(pos[0].xyz-pos[1].xyz)/2; // half the length of the line segment

vec4 posK=pos[0]+vec4(v1.xyz,0.0)+(vec4(v2.xyz,0.0)*(mag));//this is the K curve point

//line 1

gl_Position = posK;
EmitVertex();
gl_Position = pos[0];
EmitVertex();
EndPrimitive();

gl_Position = posK;
EmitVertex();
gl_Position = pos[1];
EmitVertex();

EndPrimitive();
}

Comment on Depth Shadow maps by Aviel

Aviel — Fri, 03 Jun 2011 17:19:36 +0000

I have screwed around with it, and I only bug other people as a last resort. I probably screwed something up with the buffers, because I’ve verified that my shader isn’t the problem.

Comment on Depth Shadow maps by Peter Wallström

Peter Wallström — Fri, 03 Jun 2011 14:10:22 +0000

There is no common reason for that, if it’s done right it just works, if you did something wrong it should render something even though it’s probably wrong, the only things i can think of is if your running openGL 3.x in forward compatible mode and the shader doesn’t compile (and you have no error checking) it wouldn’t render anything.
or if you happen to render something over the screen it might also go black.
Alternatively since it uses a fbo for the shadow map if you don’t switch to the back buffer nothing will ever render.
So it’s probably something you did wrong for some reason, try messing around with the code and comment out parts and see what happens.

Comment on Depth Shadow maps by Aviel

Aviel — Fri, 03 Jun 2011 06:53:08 +0000

Is there any common reason why this code might just render blackness, or have I made a very specific and serious screwup?

Comment on FBO feeedbackbuffer by Franticfreddy

Franticfreddy — Fri, 18 Mar 2011 14:18:02 +0000

thanks it help me a lot !

Comment on Running OpenGL3.0 – part3 by Daniel

Daniel — Sat, 12 Feb 2011 04:24:29 +0000

I used these at first to learn and get some basic design down for my renderer, but I moved to GLM… and my god is it much *much* faster. I’d say for most, GLM is the better alternative if your not looking to roll your own.

Comment on Running OpenGL3.0 – part3 by Peter Wallström

Peter Wallström — Wed, 05 Jan 2011 13:49:56 +0000

no, well it could work that way (and in some game engines with a strongly hierarchal object tree structure its the preferred way), but openGL before 3.0 sure didn’t, it does things the way i have done here, just “under the hood”.

Comment on Running OpenGL3.0 – part3 by Kryten

Kryten — Tue, 28 Dec 2010 15:31:04 +0000

Hm ok, maybe I didn’t understand correctly what these functions do. I thought OpenGL was some how managing a stack of matrices and these were for adding a new (identity) one to apply specific transformation (that how I use them in my current code).

What I started to code is an implementation of what I described above with final coordinates computed by multiplying all matrices in the stack and finally multiplying with the vertex coordinate.

Is it correct ?

Alexandre