Artifact in case of creation of shadowmapping

[F0rest]

When the light source moves away from the object, it creates unnecessary shadow:
[ATTACH=CONFIG]1154[/ATTACH]ok
[ATTACH=CONFIG]1155[/ATTACH]ok
[ATTACH=CONFIG]1156[/ATTACH]problem

creating shadow:

vec3 computeShadow(vec4 vPositionFromLight, sampler2D shadowSampler, float darkness, float bias)
{
	vec3 depth = vPositionFromLight.xyz / vPositionFromLight.w;
	vec2 uv = depth.xy;

	if((depth.x < 0.0)||(depth.x > 1.0) || (depth.y < 0.0) || (depth.y > 1.0) || (depth.z < 0.0) || (depth.z > 1.0))
	{
		return vec3(1.0);
	}else
	{
	float texelSize = 1.0/1024.0;
	vec3 colour = vec3(0.0);int count = 0;float shadow;
	for (int y = -2; y <= 2; ++y)
	{
		for (int x = -2; x <= 2; ++x)
		{
			vec2 offset = uv + vec2(float(x) * texelSize, float(y) * texelSize);
			if((offset.x >= 0.0) && (offset.x <= 1.0) && (offset.y >= -0.0) && (offset.y <= 0.999))
			{
				shadow = unpack(texture2D(shadowSampler, offset)) + bias;
				if ( depth.z > shadow )
				{
					colour+=vec3(1.0)*0.8;
				}
				else
				{
					colour+=vec3(1.0);
				}
				count++;
			}
		}
	}
	colour /= float(count);
	return colour;
	}
}

How to correct it?
live example

[GClements]

Is the shadow map large enough to cover the visible area?

When you render into the shadow map, are you setting the viewport to cover its full extent?

[F0rest]

shadowmap viewport=1024 px.

the problem is created in a cycle:

vec3 computeShadow(vec4 vPositionFromLight, sampler2D shadowSampler, float darkness, float bias)
{
	vec3 depth = vPositionFromLight.xyz / vPositionFromLight.w;
	vec2 uv = depth.xy;
	if((depth.x < 0.0)||(depth.x > 1.0) || (depth.y < 0.0) || (depth.y > 1.0) || (depth.z < 0.0) || (depth.z > 1.0))
	{
		return vec3(1.0);
	}else
	{
		float texelSize = 1.0/1024.0;
		vec3 colour = vec3(0.0);int count = 0;float shadow;
		vec2 offset = uv ;
		if((offset.x >= 0.0) && (offset.x <= 1.0) && (offset.y >= -0.0) && (offset.y <= 0.999))
		{
			shadow = unpack(texture2D(shadowSampler, offset)) + bias;
			if(depth.z>shadow)
			{
				colour+=vec3(1.0)*0.8;
			}
			else
			{
				colour+=vec3(1.0);
			}
		}
		return colour;
	}
}

-Problems aren’t present, but shadows aren’t smoothed

[Dark_Photon]

That the artifact is not full intensity shadow is a good clue.

Some ideas to help you nail it down. Apply these cumulatively, not just flip each on and off in isolation:

• You can’t robustly clip after the perspective divide (with the perspective frustum for your point light). Clip before.
• Are you clearing the shadow map to 1 before you render the scene into it? If not, do so.
• For testing, disable anistropic filtering.
• For testing, set NEAREST on your MIN and MAG filters (i.e. disable PCF)
• What wrap behavior do you have set on your shadow map. Change it to CLAMP_TO_EDGE.
• Are you casting anything besides the human figure (e.g. the ground plane) into the shadow map? Disable that.
• When the light source gets close to the ground plane, how are you computing the bounds of the shadow frustum. Is the size exploding?
• You’re sampling textures with implicit LOD inside conditionals. You shouldn’t do that. Read this:
  ** Derivatives I: Derivatives and Discontinuities (The Hacks of Life: Derivatives I: Discontinuities and Gradients)
  ** Derivatives II: Conditional Texture Fetches (The Hacks of Life: Derivatives II: Conditional Texture Fetches)
• In your second shader, if you change (offset.y <= 0.999) to (offset.y <= 1.0 ), does the problem re-appear?
• Is it possible your math to back-project the eye-space vertices of the ground plane back into light (shadow) space isn’t right? Try munging the eye-space depth value to 0, 0.5, or 1?