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GLSL spotlight+scale problem


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#1 junkyska   Members   -  Reputation: 143

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Posted 10 July 2012 - 03:32 PM

Hi everyone,

I have a problem with my shaders. I implemented a phong lightning. In the shader vertices get transformed by position, rotation and scale.
The problems is that when the scale is not (1, 1, 1) I get wrong results (displaced lighting). It's really noticeable for example with scale (100, 20, 100). I see this bug when I was testing with spotlight, so directional light and point light can also be wrong.

I think it's scale+normals problem, but I can't find it. Normal Matrix has scale in accound? How can I deal with this problem? If someone can help me I will be really apreciated. Any other advice not related to this problem it will be wellcome.
If it will help I can upload some images.

(SpotFallOff its usless, I use SpotInnerCutOff and SpotOuterCutOff)

Sorry for my bad English.

Here is my Shader:
<Shader>
<ShaderPart type="Vertex">
  <ShaderCode>
   <![CDATA[  
   #version 420
   uniform mat4 ModelViewMatrix;
   uniform mat4 MVP;
   uniform mat3 NormalMatrix;
  
   in vec3 in_Position;
   in vec3 in_Normal;
   in vec3 in_Tangent;
   in vec3 in_Bitangent;
   in vec2 in_TexCoord;
  
   out mat3 TBN;
   out vec2 pTexCoord;
   out vec3 pViewDir;
   out vec3 pPosition;
   out vec3 pVertexPos;
  
   void main(void)
   {
	pTexCoord = in_TexCoord;
  
	vec3 n = normalize(NormalMatrix * in_Normal);
	vec3 t = normalize(NormalMatrix * in_Tangent);
	vec3 b = -normalize( cross(n, t) );
	TBN = mat3(
	 t.x, b.x, n.x,
	 t.y, b.y, n.y,
	 t.z, b.z, n.z );
	
	pPosition = vec3( ModelViewMatrix * vec4(in_Position, 1.0) );
	pViewDir = TBN * vec3(-pPosition);
	pVertexPos = in_Position;
	gl_Position =  MVP * vec4(in_Position, 1.0);
   }
   ]]>
  </ShaderCode>
</ShaderPart>
<ShaderPart type="Fragment" >
  <ShaderCode>
   <![CDATA[
   #version 420
  
   uniform sampler2D Texture0; // Diffuse
   uniform sampler2D Texture1; // Normal
   uniform sampler2D Texture2; // Specular
  
   uniform float SpecularPower;
  
   uniform struct
   {
	vec3 ambient;
	vec3 diffuse;
	vec3 specular;
  
	float constantAtt;
	float linearAtt;
	float quadraticAtt;
  
	float spotInnerCutOff;
	float spotOuterCutOff;
	float spotFallOff;
  
	vec3 position;
	vec3 direction; // For Spot and Directional lights
  
	int type; // 0-> Point, 1-> Spot, 2-> Directional
   }
   Lights[16];
   uniform int NumLights;
  
   in mat3 TBN;
   in vec2 pTexCoord;
   in vec3 pViewDir;
   in vec3 pPosition;
   in vec3 pVertexPos;
  
   out vec4 fragColor;
  
   vec4 computePhongPointLight(in int index)
   {
	vec3 color = vec3(0.0);
  
	vec4 difColor = texture2D( Texture0, pTexCoord );
	vec3 normColor = normalize(texture2D( Texture1, pTexCoord ).xyz * 2.0 - 1.0);
	vec3 specColor = texture2D( Texture2, pTexCoord ).rgb;
  
	vec3 lightDir = TBN * (Lights[index].position.xyz - pPosition);
  
	// Normalized lightDir
	vec3 lightDirNorm = normalize( lightDir );
  
	vec3 r = reflect( -lightDirNorm, normColor );
  
	float sDotN = max( dot(lightDirNorm, normColor), 0.0 );
  
	// Compute att for point and spot lights. Directional lights has att = 1.0
	float att = 1.0;
	float distSqr = dot(lightDir, lightDir);
	float invAtt = (Lights[index].constantAtt + (Lights[index].linearAtt*sqrt(distSqr)) + (Lights[index].quadraticAtt*distSqr));
	att = 0.0;
	if (invAtt != 0.0)
	 att = 1.0/invAtt;
  
	vec3 diffuse = difColor.rgb * Lights[index].diffuse * sDotN;
	vec3 ambient = difColor.rgb * Lights[index].ambient; // Cheat here
	// Specular power
	vec3 specular = vec3(0.0);
	if ( sDotN > 0.0 )
	{
	 specular = Lights[index].specular.rgb * specColor * pow( max( dot(r, normalize(pViewDir)), 0.0), SpecularPower );
	}  
  
	color = (diffuse + specular + ambient)*att;
	return vec4(color, difColor.a);
   }
  
   vec4 computePhongSpotLight(in int index)
   {
	vec3 color = vec3(0.0);
  
	vec4 difColor = texture( Texture0, pTexCoord );
	vec3 normColor = normalize(texture( Texture1, pTexCoord ).xyz * 2.0 - 1.0);
	vec3 specColor = texture( Texture2, pTexCoord ).rgb;
  
	vec3 lightDir = TBN * (Lights[index].position.xyz - pPosition);
  
	// Normalized lightDir
	vec3 lightDirNorm = normalize( lightDir );
  
	vec3 r = reflect( -lightDirNorm, normColor );
  
	float sDotN = max( dot(lightDirNorm, normColor), 0.0 );
  
	// Compute att for point and spot lights. Directional lights has att = 1.0
	float att = 1.0;
	float distSqr = dot(lightDir, lightDir);
	float invAtt = (Lights[index].constantAtt + (Lights[index].linearAtt*sqrt(distSqr)) + (Lights[index].quadraticAtt*distSqr));
	att = 0.0;
	if (invAtt != 0.0)
	 att = 1.0/invAtt;
	
	// Compute spot
	float cos_cur_angle = dot(-lightDirNorm, normalize(TBN * Lights[index].direction));
	float cos_inner_cone_angle = cos(Lights[index].spotInnerCutOff);
	float cos_outer_cone_angle = cos(Lights[index].spotOuterCutOff);
	float cos_inner_minus_outer_angle = cos_inner_cone_angle - cos_outer_cone_angle;
	float spot = clamp((cos_cur_angle - cos_outer_cone_angle) / cos_inner_minus_outer_angle, 0.0, 1.0);
  
	vec3 diffuse = difColor.xyz * Lights[index].diffuse * sDotN;
	vec3 ambient = difColor.rgb * Lights[index].ambient; // Cheat here
  
	// Specular power
	vec3 specular = vec3(0.0);
	if ( sDotN > 0.0 )
	{
	 specular = Lights[index].specular.rgb * specColor * pow( max( dot(r, normalize(pViewDir)), 0.0), SpecularPower );  
	}
  
	color = (diffuse + specular + ambient)*att*spot;
	return vec4(color, difColor.a);
   }
  
   vec4 computePhongDirectionalLight(in int index)
   {
	vec3 color = vec3(0.0);
  
	vec4 difColor = texture( Texture0, pTexCoord );
	vec3 normColor = normalize(texture( Texture1, pTexCoord ).xyz * 2.0 - 1.0);
	vec3 specColor = texture( Texture2, pTexCoord ).rgb;
  
	vec3 lightDir = TBN * Lights[index].direction;
  
	// Normalized lightDir
	vec3 lightDirNorm = normalize( lightDir );
  
	vec3 r = reflect( -lightDirNorm, normColor );
  
	float sDotN = max( dot(lightDirNorm, normColor), 0.0 );
  
	vec3 diffuse = difColor.rgb * Lights[index].diffuse * sDotN;
	vec3 ambient = difColor.rgb * Lights[index].ambient; // Cheat here
  
	// Specular power
	vec3 specular = vec3(0.0);
	if ( sDotN > 0.0 )
	{
	 specular = Lights[index].specular.rgb * specColor * pow( max( dot(r, normalize(pViewDir)), 0.0), SpecularPower );
	}
  
	color = diffuse + specular + ambient;
	return vec4(color, difColor.a);
   }
  
   vec4 computeLight(in int index)
   {
	if (Lights[index].type == 0)
	 return computePhongPointLight(index);
	if (Lights[index].type == 1)
	 return computePhongSpotLight(index);
	else if (Lights[index].type == 2)
	 return computePhongDirectionalLight(index);
   }
   void main(void)
   {
	fragColor = vec4(0.0, 0.0, 0.0, 1.0);
	for (int i = 0; i < NumLights; i++)
	 fragColor += computeLight(i);
	
	if (fragColor.a < 0.5)
	 discard;
   }
   ]]>
  </ShaderCode>
</ShaderPart>
</Shader>


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#2 SaTANO   Members   -  Reputation: 418

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Posted 10 July 2012 - 11:45 PM

Well you are probably right. It depends on how you calculate this matrix.
When matrix scale is non uniform normal matrix is not simple 3x3 matrix from your 4x4 modelview matrix

You should check this:
http://www.lighthouse3d.com/tutorials/glsl-tutorial/the-normal-matrix/

#3 junkyska   Members   -  Reputation: 143

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Posted 12 July 2012 - 02:32 PM

I think it's well calculated normal matrix.
I don't know where is the bug, I can't find it.

Here is my normal matrix calculation:
    _currentRenderableInfo.renderablePos = actor->getDerivedPosition();
    _currentRenderableInfo.renderableRot = actor->getDerivedRotation();
    _currentRenderableInfo.renderableScale = actor->getDerivedScale();
    _currentRenderableInfo.modelMatrix = actor->getFullTransform();
    _currentRenderableInfo.modelViewMatrix = _currentViewInfo.viewMatrix * _currentRenderableInfo.modelMatrix;
    _currentRenderableInfo.mvpMatrix = _currentViewInfo.projectionMatrix * _currentRenderableInfo.modelViewMatrix;
    _currentRenderableInfo.normalMatrix = Core::transpose(Core::inverse(Core::mat3(_currentRenderableInfo.modelViewMatrix)));





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