[SOLVED] Trying to use Atmospheric Scattering (O'Neill 2004) but get black sphere.

Hi guys and girls, I'm trying to use Atmospheric Scattering (O'Neill 2004) but only get black sphere. The shaders being used are 99% copy/pasted from GPU gems 2, but with comments removed (comments won't compile for some reason).

I've tried changing gl_FrontColor to see if the faces are in the wrong direction, but I can set a color and see it pass through the fragment shader just fine. However, using the actual scattering algorithm is a no go right now and I can't figure out what's causing it to zero out. Am I missing something?

For reference, here they are:

Vertex Shader:

uniform vec3 v3CameraPos;uniform vec3 v3LightPos;		uniform vec3 v3InvWavelength;	uniform float fCameraHeight;	uniform float fCameraHeight2;	uniform float fOuterRadius;		uniform float fOuterRadius2;	uniform float fInnerRadius;		uniform float fInnerRadius2;	uniform float fKrESun;			uniform float fKmESun;			uniform float fKr4PI;			uniform float fKm4PI;		uniform float fScale;			uniform float fScaleDepth;		uniform float fScaleOverScaleDepth;const int nSamples = 4;const float fSamples = 4.0;varying vec3 v3Direction;float scale(float fCos){	float x = 1.0 - fCos;	return fScaleDepth * exp(-0.00287 + x*(0.459 + x*(3.83 + x*(-6.80 + x*5.25))));}void main(void){	vec3 v3Pos = gl_Vertex.xyz;	vec3 v3Ray = v3Pos - v3CameraPos;	float fFar = length(v3Ray);	v3Ray /= fFar;	vec3 v3Start = v3CameraPos;	float fHeight = length(v3Start);	float fDepth = exp(fScaleOverScaleDepth * (fInnerRadius - fCameraHeight));	float fStartAngle = dot(v3Ray, v3Start) / fHeight;	float fStartOffset = fDepth*scale(fStartAngle);	float fSampleLength = fFar / fSamples;	float fScaledLength = fSampleLength * fScale;	vec3 v3SampleRay = v3Ray * fSampleLength;	vec3 v3SamplePoint = v3Start + v3SampleRay * 0.5;	vec3 v3FrontColor = vec3(0.0, 0.0, 0.0);	for(int i=0; i<nSamples; i++)	{		float fHeight = length(v3SamplePoint);		float fDepth = exp(fScaleOverScaleDepth * (fInnerRadius - fHeight));		float fLightAngle = dot(v3LightPos, v3SamplePoint) / fHeight;		float fCameraAngle = dot(v3Ray, v3SamplePoint) / fHeight;		float fScatter = (fStartOffset + fDepth*(scale(fLightAngle) - scale(fCameraAngle)));		vec3 v3Attenuate = exp(-fScatter * (v3InvWavelength * fKr4PI + fKm4PI));		v3FrontColor += v3Attenuate * (fDepth * fScaledLength);		v3SamplePoint += v3SampleRay;	}	gl_FrontSecondaryColor.rgb = v3FrontColor * fKmESun;	gl_FrontColor.rgb = v3FrontColor * (v3InvWavelength * fKrESun);		gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;	v3Direction = v3CameraPos - v3Pos;}

Fragment Shader:

uniform vec3 v3LightPos;uniform float g;uniform float g2;varying vec3 v3Direction;void main (void){	float fCos = dot(v3LightPos, v3Direction) / length(v3Direction);	float fMiePhase = 1.5 * ((1.0 - g2) / (2.0 + g2)) * (1.0 + fCos*fCos) / pow(1.0 + g2 - 2.0*g*fCos, 1.5);	gl_FragColor = gl_Color + fMiePhase * gl_SecondaryColor;	gl_FragColor.a = gl_FragColor.b;}

And here is how I feed the parameters into the shader:

glUseProgram(sky_shader);	//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);		GLint v3CameraPos, v3LightPos, v3InvWavelength, 		fCameraHeight, fCameraHeight2, 		fInnerRadius, fInnerRadius2, fOuterRadius, fOuterRadius2, 		fKrESun, fKmESun, fKr4PI, fKm4PI, fScale, fScaleDepth, fScaleOverScaleDepth,		g, g2;		glGetUniformLocation(v3CameraPos, "v3CameraPos");	glUniform3f(v3CameraPos, 0, 1, 0);	glGetUniformLocation(v3LightPos, "v3LightPos");	glUniform3f(v3LightPos, sun_x / sqrt(sun_x * sun_x + sun_y * sun_y), sun_y / sqrt(sun_x * sun_x + sun_y * sun_y), 0);	glGetUniformLocation(v3InvWavelength, "v3InvWavelength");	glUniform3f(v3InvWavelength, 1.0 / pow(0.650, 4.0), 1.0 / pow(0.570, 4.0), 1.0 / pow(0.475, 4.0));	glGetUniformLocation(fCameraHeight, "fCameraHeight");	glUniform1fARB(fCameraHeight, 1);	glGetUniformLocation(fCameraHeight2, "fCameraHeight2");	glUniform1fARB(fCameraHeight2, 1);	glGetUniformLocation(fInnerRadius, "fInnerRadius");	glUniform1fARB(fInnerRadius, 6356.7523142);	glGetUniformLocation(fInnerRadius2, "fInnerRadius2");	glUniform1fARB(fInnerRadius2, 6356.7523142 * 6356.7523142);	glGetUniformLocation(fOuterRadius, "fOuterRadius");	glUniform1fARB(fOuterRadius, 6452.103598913);	glGetUniformLocation(fOuterRadius2, "fOuterRadius2");	glUniform1fARB(fOuterRadius2, 6452.103598913 * 6452.103598913);	glGetUniformLocation(fKrESun, "fKrESun");	glUniform1fARB(fKrESun, 0.0025 * 20.0);	glGetUniformLocation(fKmESun, "fKmESun");	glUniform1fARB(fKmESun, 0.0015 * 20.0);	glGetUniformLocation(fKr4PI, "fKr4PI");	glUniform1fARB(fKr4PI, 0.0025 * 4.0 * 3.141592653);	glGetUniformLocation(fKm4PI, "fKm4PI");	glUniform1fARB(fKm4PI, 0.0015 * 4.0 * 3.141592653);	glGetUniformLocation(fScale, "fScale");	glUniform1fARB(fScale, 1.0 / (6452.103598913 - 6356.7523142));	glGetUniformLocation(fScaleDepth, "fScaleDepth");	glUniform1fARB(fScaleDepth, 0.25);	glGetUniformLocation(fScaleOverScaleDepth, "fScaleOverScaleDepth");	glUniform1fARB(fScaleOverScaleDepth, 4.0 / (6452.103598913 - 6356.7523142));	glGetUniformLocation(g, "g");	glUniform1fARB(g, -0.85);	glGetUniformLocation(g2, "g2");	glUniform1f(g2, -0.85 * -0.85);

Rendering:

glRotated(CAMERA->rotation->x, 1, 0, 0);	glRotated(CAMERA->rotation->y, 0, 1, 0);	glTranslated(0,-EARTH_RADIUS -CAMERA->position->y / 1000,0);	gluSphere(sky_sphere, EARTH_ATMOSPHERE_RADIUS, 128, 128);

[Edited by - DanoruX on January 3, 2011 2:08:02 PM]

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