Hello!

I am having a big problem implementing VSM and I have been stucked for a couple of days.

When I use VSM instead of a basic shadow mapping, shadows behave strangely. I think the shadow map that I am generating is good, so I dont understand what is happening.

This is the code I use to generate this dual channel depth map:

for (int i = 0; i < SHADOWMAP_CASCADE_COUNT; i++)
	{
		//generamos los shadowmaps originales, donde se renderizara la escena

		glBindFramebuffer(GL_FRAMEBUFFER, lightFrameBuffer[i]);
		glBindTexture(GL_TEXTURE_2D, shadowmapTexture[i]);

		glTexImage2D(GL_TEXTURE_2D, 0, GL_RG32F, SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_RGBA, GL_FLOAT, 0);
		glUniform1i(glGetUniformLocation(program, varName), 3); // para testear en el programa pasado, en el plane program, ni caso
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
		float borderColor[] = { 1.0f, 1.0f, 1.0f, 1.0f };
		glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, shadowmapTexture[i], 0);
		glColorMask(GL_TRUE, GL_TRUE, GL_FALSE, GL_FALSE);
	}

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This is the glsl code I use to store the depth to the texture:

 float depth = v_Position.z / v_Position.w;
	depth = depth * 0.5 + 0.5;

	float moment1 = depth;
	float moment2 = depth * depth;

	float dx = dFdx(depth);
	float dy = dFdy(depth);
	moment2 += 0.25*(dx*dx+dy*dy);
	out_Color = vec4( moment1, moment2, 0.0, 1.0);

And the code to create shadows:

float shadow(int frustaIndex) //variance shadow mapping
{
	vec2 moments;
	float p;
	float variance;
	float compare;
	float d;
	float pMax;

	vec4 calcPos;
	calcPos = shadowMapPos[frustaIndex] / shadowMapPos[frustaIndex].w;
	calcPos = calcPos * 0.5 + 0.5;

	compare =  calcPos.z;

	if(frustaIndex == 2)
	{
		 moments = texture2D(shadowmap3, calcPos.xy).rg;
	
		 if (compare <= moments.x)
			return 1.0f;

		variance = moments.y - ( moments.x*moments.x );
		variance = max( variance, 0.00002 );

		 d = compare - moments.x;
		 pMax = variance / (variance + d*d);
		return pMax;	 
	}
	//here I do the same for the other frustums, changing the shadowmap (CSM it works because normal shadow mapping works, so the problem is not there)
}

And the result of all of this:

Hope someone can help me a bit! 

Thank you!

I solved it already

Care to share your solution so others looking can follow along?

To solve this problem I had to change this: float depth = v_Position.z / v_Position.w;

and write this: float depth = gl_FragCoord.z / gl_FragCoord.w;