src/shaders/terrainshader.frag

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#version 430

// ===== Uniform Buffers =====

struct LightParam {
    vec3 pos;       
    float isDir;    
    vec3 color;     
    float specExp;  
};

layout(std140, binding = 0) uniform LightInfo 
{
    LightParam lights[2];
};


// ===== Uniforms =====

uniform vec3 camPos;                
uniform vec3 size;                  
uniform sampler2D terr_texUnit;     
uniform sampler2D height_texUnit;   


// ===== In/Out params =====

in vec3 out_Normal;                 
in vec2 out_TexCoord;               
in vec3 out_ObjPos;                 

out vec4 out_Color;                 


// ===== Variables needed =====

// Light vectors
vec3 r;                             
vec3 s;                             
vec3 eye;                           

// Lighting (the Phong model).
float kamb;                         
float kdiff;                        
float kspec;                        

vec3 ambLight;                      
vec3 diffLight;                     
vec3 specLight;                     
vec3 totalLight;                    


void main(void)
{
    // Incident and reflected light is calculated for the light source.
    s = normalize(lights[0].pos - (1 - lights[0].isDir) * out_ObjPos);
    r = normalize(2 * out_Normal * dot(s, normalize(out_Normal)) - s);

    // eye vector is calculated.
    eye = normalize(camPos - out_ObjPos);

    // Light according to the Phong model.
    kamb = 0.1;
    kdiff = 0.5;
    kspec = 0.5;
    ambLight = kamb * vec3(1.0, 1.0, 1.0);
    diffLight = vec3(0.0, 0.0, 0.0);
    specLight = vec3(0.0, 0.0, 0.0);
    // Diffuse light.
    diffLight += kdiff * lights[0].color * max(0.0, dot(s, normalize(out_Normal)));
    // Specular light.
    specLight += kspec * lights[0].color * max(0.0, pow(dot(r, eye), lights[0].specExp));

    totalLight = vec3(0.0, 0.0, 0.0);
    // The different light components are added to the total light.
    totalLight += ambLight;
    totalLight += diffLight;
    totalLight += specLight;

    vec3 terrainData = vec3(texture(terr_texUnit, out_TexCoord)) * totalLight;
    out_Color = vec4(terrainData, 1.0f);
}