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some basic GLSL fragment shader show casing physical correct lighting
in vec3 normal;
in vec3 eye;//from vertex to eye/origin
const light = vec3(0.12708472893924555, -2.5399460893115735, 2.8320502943377743) // from vertex to lightsource
const vec3 LIGHT_COLOR = vec3(1, 0.7, 0.4);
//created textures have to have realistic values
//Fresh asphalt 0.04
//Worn asphalt 0.12
//Bare soil 0.17
//Green grass 0.25
//Desert sand 0.40
//New concrete 0.55
//Fresh snow 0.80–0.90
const vec3 directDiffuse = vec3(0.5);//normal diffuse color, from a texture i.e.
//the following values should be used:
//No value under 0.02
// gemstones 0.05-0.17
// liquids 0.02-0.04
//Skin 0.028
// when no idea set value of 0.04 (around plastic)
// for metals:
//Silver 0.971519 0.959915 0.915324
//Aluminium 0.913183 0.921494 0.924524
//Gold 1 0.765557 0.336057
//Copper 0.955008 0.637427 0.538163
const vec3 specColor = vec3(0.0225);
//how shiny things should be
const float gloss = 0.9;
const float SpecularPower = exp2(10 * gloss + 1);
const float normFactor = ((SpecularPower + 2) / 8 );
//about textures: directDiffuse, specColor or gloss can of course be read from textures or mixed with uniforms before they are used.
//remember when you want to use a diffuse texture that to have gamma correct colors to linearize the color after the texture read
// e.g. vec4 diff = toLinear(texture(sampler, uv))
vec4 toLinear(vec4 x){ return pow(x, vec4(2.2)) }
vec4 toGamma(vec4 x){ return pow(x, vec4(1/2.2)) }
float saturate(float a)
{
return min(1,max(0,a));
}
#define OneOnLN2_x6 8.656170 // == 1/ln(2) * 6 (6 is SpecularPower of 5 + 1)
vec3 FresnelSchlick(vec3 E,vec3 H)
{
return specColor + (1.0f - specColor) * exp2(-OneOnLN2_x6 * saturate(dot(E, H)));
}
float BlinnPhong(vec3 N, vec3 H)
{
return pow(saturate(dot(N, H)), SpecularPower);
}
vec3 light(vec3 N, vec3 V, vec3 L, vec3 lightColor)
{
vec3 H = normalize(L+V);
float NdotL = dot(N, L);
vec3 directSpecular = FresnelSchlick(L, H) * BlinnPhong(N, H) * normFactor;
return (directDiffuse + directSpecular) * lightColor * max(0,NdotL);
}
void main()
{
vec3 N = normalize(normal);
vec3 V = normalize(eye);
vec3 L = normalize(light);
vec3 color = light(N, V, L, LIGHT_COLOR);
//color += ... now add other lightsource or ambient light(directDiffuse * ambientLigthColor)
FragColor = toGamma(vec4(color, 1));
}
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