How's this:
//
// Fragment shader for environment mapping with an
// equirectangular 2D texture and refraction mapping
// with a background texture blended together using
// the fresnel terms
//
// Author: Jon Kennedy, based on the envmap shader by John Kessenich, Randi Rost
//
// Copyright (c) 2002-2005 3Dlabs Inc. Ltd.
//
// See 3Dlabs-License.txt for license information
//
const vec3 Xunitvec = vec3 (1.0, 0.0, 0.0);
const vec3 Yunitvec = vec3 (0.0, 1.0, 0.0);
uniform vec3 BaseColor;
uniform float Depth;
uniform float MixRatio;
// need to scale our framebuffer - it has a fixed width/height of 2048
uniform float FrameWidth;
uniform float FrameHeight;
uniform sampler2D EnvMap;
uniform sampler2D RefractionMap;
varying vec3 Normal;
varying vec3 EyeDir;
varying vec4 EyePos;
varying float LightIntensity;
void main (void)
{
// Compute reflection vector
vec3 reflectDir = reflect(EyeDir, Normal);
// Compute altitude and azimuth angles
vec2 index;
index.y = dot(normalize(reflectDir), Yunitvec);
reflectDir.y = 0.0;
index.x = dot(normalize(reflectDir), Xunitvec) * 0.5;
// Translate index values into proper range
if (reflectDir.z >= 0.0)
index = (index + 1.0) * 0.5;
else
{
index.t = (index.t + 1.0) * 0.5;
index.s = (-index.s) * 0.5 + 1.0;
}
// if reflectDir.z >= 0.0, s will go from 0.25 to 0.75
// if reflectDir.z < 0.0, s will go from 0.75 to 1.25, and
// that's OK, because we've set the texture to wrap.
// Do a lookup into the environment map.
vec3 envColor = vec3 (texture2D(EnvMap, index));
// calc fresnels term. This allows a view dependant blend of
reflection/refraction
float fresnel = abs(dot(normalize(EyeDir), Normal));
fresnel *= MixRatio;
fresnel = clamp(fresnel, 0.1, 0.9);
// calc refraction
vec3 refractionDir = normalize(EyeDir) - normalize(Normal);
// Scale the refraction so the z element is equal to depth
float depthVal = Depth / -refractionDir.z;
// perform the div by w
float recipW = 1.0 / EyePos.w;
vec2 eye = EyePos.xy * vec2(recipW);
// calc the refraction lookup
index.s = (eye.x + refractionDir.x * depthVal);
index.t = (eye.y + refractionDir.y * depthVal);
// scale and shift so we're in the range 0-1
index.s = index.s / 2.0 + 0.5;
index.t = index.t / 2.0 + 0.5;
// as we're looking at the framebuffer, we want it clamping at
the edge of the rendered scene, not the edge of the texture,
// so we clamp before scaling to fit
float recip1k = 1.0 / 2048.0;
index.s = clamp(index.s, 0.0, 1.0 - recip1k);
index.t = clamp(index.t, 0.0, 1.0 - recip1k);
// scale the texture so we just see the rendered framebuffer
index.s = index.s * FrameWidth * recip1k;
index.t = index.t * FrameHeight * recip1k;
vec3 RefractionColor = vec3 (texture2D(RefractionMap, index));
// Add lighting to base color and mix
vec3 base = LightIntensity * BaseColor;
envColor = mix(envColor, RefractionColor, fresnel);
envColor = mix(envColor, base, .0);
gl_FragColor = vec4 (envColor, 1.0);
}
On 4/18/06, Nicolas Boulay <[EMAIL PROTECTED]> wrote:
> Look up into texture seems complicated.
>
> http://oss.sgi.com/projects/ogl-sample/registry/ARB/GLSLangSpec.Full.1.10.59.pdf
>
> show function as :
> vec4 texture1DProj (sampler1D sampler, vec4 coord [, float bias] )
>
> That's quite complexe.
>
> Inside http://www.lighthouse3d.com/opengl/glsl/index.php?texture we see :
> uniform sampler2D tex;
>
> void main()
> {
> vec4 color = texture2D(tex,gl_TexCoord[0].st);
> gl_FragColor = color;
> }
>
> So, texture2D take a pointer and a vector. That's a lot more simple than
> previous function. But what is used today ?
> GLSL propose a lot of functionalities. What is needed is real world example.
> I
> need to know what is performance critical in current shader.
>
> Nicolas Boulay
>
> Le lundi 17 Avril 2006 17:03, Timothy Miller a écrit :
> > I've been thinking about programmable shaders and what we should
> > implement. If we have some reasonable way to load immediate values
> > into vectors, then we can subsume all of the following into a single
> > dot product primitive:
> > - scalar adds and subtracts
> > - scalar multiplies
> > - vector dot product
> > - matrix multiply
> >
> > We'll need a few other things like computing reciprocols (for
> > divides), vector sums and vector multiplies. (Later today, when I
> > have time, I'll produce a more formal and precise description of the
> > primitives I have in mind.)
> >
> > Anyhow, it seems to me that we should look at some examples. There
> > are two things we can do here. Some people with experience can write
> > out, in high-level pseudo-code, some simple shader programs. And
> > someone else could look at the OGA "model" and convert that into the
> > pseudo code corresponding to how it would be fully implemented in a
> > programmable shader (some details can be left out).
> >
> > This will help us figure out which primitives we need. And from
> > experience later, we can figure out where we might benefit from adding
> > a few more and optimizing some things.
> > _______________________________________________
> > Open-graphics mailing list
> > [email protected]
> > http://lists.duskglow.com/mailman/listinfo/open-graphics
> > List service provided by Duskglow Consulting, LLC (www.duskglow.com)
> _______________________________________________
> Open-graphics mailing list
> [email protected]
> http://lists.duskglow.com/mailman/listinfo/open-graphics
> List service provided by Duskglow Consulting, LLC (www.duskglow.com)
>
--
I think computer viruses should count as life. I think it says
something about human nature that the only form of life we have
created so far is purely destructive. We've created life in our own
image. (Stephen Hawking)
_______________________________________________
Open-graphics mailing list
[email protected]
http://lists.duskglow.com/mailman/listinfo/open-graphics
List service provided by Duskglow Consulting, LLC (www.duskglow.com)
