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Multiples Point Light


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#1 VitaliBR   Members   -  Reputation: 147

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Posted 08 August 2012 - 09:18 PM

Hi!

I anticipate that I already have trouble with shaders :(

I would create several "point light" using HLSL, where I can create a PointLight in a class.For exemple:
PointLight* light1;
PointLight* light3;
PointLight* light2;
//....

light1 = new PointLight();
light2 = new PointLight();
light3 = new PointLight();
//....

I found this demo, but the 8 lights are created within the. Fx, how do I create a light class in the code?

http://www.dhpoware.com/demos/d3d9MultiplePointLights.html


Thanks :)

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#2 SamiHuutoniemi   Members   -  Reputation: 259

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Posted 09 August 2012 - 04:12 AM

You are not making much sense! Are you talking about how to write your shader HLSL code or your C++ code? Or do you not know the difference?

Edited by SamiHuutoniemi, 09 August 2012 - 04:12 AM.


#3 VitaliBR   Members   -  Reputation: 147

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Posted 09 August 2012 - 04:31 AM

You are not making much sense! Are you talking about how to write your shader HLSL code or your C++ code? Or do you not know the difference?


Sorry SamiHuutoniemi,

My english ir very poor :(

I'll put an example, I have a scene with several 3D models (OBJ format for example), and would create five point lights to the scene using HLSL, but I would like to create 5 lights in 5 objects of a class.

In this example:
http://www.dhpoware.com/demos/d3d9MultiplePointLights.html

The author has created one .fx (HLSL) where it creates a shader to be within the desired number of lights
//-----------------------------------------------------------------------------
// Pixel Shaders.
//-----------------------------------------------------------------------------
float4 PS_SinglePassPointLighting(VS_OUTPUT IN) : COLOR
{
    float4 color = float4(0.0f, 0.0f, 0.0f, 0.0f);
   
    float3 n = normalize(IN.normal);
    float3 v = normalize(IN.viewDir);
    float3 l = float3(0.0f, 0.0f, 0.0f);
    float3 h = float3(0.0f, 0.0f, 0.0f);
   
    float atten = 0.0f;
    float nDotL = 0.0f;
    float nDotH = 0.0f;
    float power = 0.0f;
   
    for (int i = 0; i < MAX_POINT_LIGHTS; ++i)
    {
	    l = (lights[i].pos - IN.worldPos) / lights[i].radius;
	    atten = saturate(1.0f - dot(l, l));
	   
	    l = normalize(l);
	    h = normalize(l + v);
	   
	    nDotL = saturate(dot(n, l));
	    nDotH = saturate(dot(n, h));
	    power = (nDotL == 0.0f) ? 0.0f : pow(nDotH, material.shininess);
	   
	    color += (material.ambient * (globalAmbient + (atten * lights[i].ambient))) +
				 (material.diffuse * lights[i].diffuse * nDotL * atten) +
				 (material.specular * lights[i].specular * power * atten);
    }
				  
return color * tex2D(colorMap, IN.texCoord);
}

But I like to do instead, create a desired number of lights in my C++ code using a class made ​​for light eg.

How should my shader (HLSL)? This is possible? and because the example he made the desired number of lights in the fx file?

#4 Tasaq   Members   -  Reputation: 1218

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Posted 09 August 2012 - 04:47 AM

You should make something like that:

for every object
for every light
render the scene with light[i] (light[i] contains light color, intensity, distance etc.)

If you want to have a lot of point lights, check out deferred rendering (but be warned, if you are beginner with shaders and programming it might be very hard).

#5 VitaliBR   Members   -  Reputation: 147

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Posted 09 August 2012 - 04:56 AM

You should make something like that:

for every object
for every light
render the scene with light[i] (light[i] contains light color, intensity, distance etc.)

If you want to have a lot of point lights, check out deferred rendering (but be warned, if you are beginner with shaders and programming it might be very hard).


Like this?



#6 Tasaq   Members   -  Reputation: 1218

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Posted 09 August 2012 - 07:44 AM

Like this?


It's just end result :)

Wiki gives basic idea : http://en.wikipedia.org/wiki/Deferred_shading

If You want to make outdoor scene use traditional methoods though. You gain from deferred if you want to make a night or indoor scene with tons of lights ;)
Much more details here : http://developer.download.nvidia.com/assets/gamedev/docs/6800_Leagues_Deferred_Shading.pdf

#7 Hodgman   Moderators   -  Reputation: 29542

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Posted 09 August 2012 - 07:54 AM

for (int i = 0; i < MAX_POINT_LIGHTS; ++i)
{
color += (material.ambient * (globalAmbient + (atten * lights[i].ambient))) +
(material.diffuse * lights[i].diffuse * nDotL * atten) +
(material.specular * lights[i].specular * power * atten);

If you shader uses code like this, then I assume at the beginning of the shader, there is something like:
struct Light
{
  float4 ambient;
  float4 diffuse;
  float4 specular;
};
#define MAX_POINT_LIGHTS 4
Light lights[MAX_POINT_LIGHTS];
If so, then to represent a light in C++, you can use the same struct:
struct float4 { float x, y, z, w; };
struct Light{
  float4 ambient;
  float4 diffuse;
  float4 specular;
};
Light* light1 = new Light;


#8 french_hustler   Members   -  Reputation: 350

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Posted 09 August 2012 - 11:47 AM

As Hodgman mentioned, your C++ code light structs should mirror your shader light structs (making sure you have the right padding).

If you do want to have an arbitrary amount of lights to be defined by your C++ code, there a couple ways of doing so (without deferred rendering):

1: have different shaders with different light #'s. This way is a bit sketchy though since you are still restricted to a certain number of lights depending on which shader you run.

2: if your hardware allows it, you could use dynamic branching. You could define a constant in your shader (gNumLights) that specifies the amount of lights you'll be sending over to the gpu. You will still have a MAX_POINT_LIGHTS, but you'll be able to define in C++ how many lights you have in your scene in the range of [0, MAX_POINT_LIGHTS]. Then when you do your lighting, you just iterate through your light array from 0 to gNumLights.

Edited by french_hustler, 09 August 2012 - 11:47 AM.





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