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#version 330 core
in vec2 texCoord0;
in vec3 normal0;
in float height;
uniform sampler2D sampler;
uniform vec3 lightDirection;
uniform vec3 lightColor;
uniform vec3 ambientColor;
const vec3 grass = vec3(.1, .4, .05);
const vec3 slope = vec3(.6, .6, .4);
const vec3 rock = vec3(.2, .2, .1);
const vec3 sand = vec3(.76, .7, .5);
const vec3 snow = vec3(.97, .97, .99);
const float beachline = .5;
const float snowline_low = 28;
const float snowline_high = 30;
const float slope_min = .99;
const float slope_mid = .95;
const float slope_max = .90;
vec3
mixBetween(vec3 colA, vec3 colB, float blend, float low, float high)
{
return mix(colA, colB, (blend - low) / (high - low));
}
void
main()
{
vec4 tex = texture(sampler, texCoord0);
gl_FragColor = tex;
gl_FragColor.rgb *= clamp(ambientColor + (dot(-lightDirection, normal0) * lightColor), 0.0, 1.0);
if (height < beachline) { // Sandy beach
gl_FragColor.rgb *= sand;
}
else if (normal0.z < slope_max) { // Dark rocky face
gl_FragColor.rgb *= rock;
}
else { // Colour by lesser slope
if (normal0.z < slope_mid) {
gl_FragColor.rgb *= mixBetween(rock, slope, normal0.z, slope_max, slope_mid);
}
else if (normal0.z < slope_min) {
gl_FragColor.rgb *= mixBetween(slope, grass, normal0.z, slope_mid, slope_min);
}
else {
gl_FragColor.rgb *= grass;
}
// Add a snow covering
if (height > snowline_low) {
vec3 tsnow = tex.rgb * snow;
if (height > snowline_high) {
gl_FragColor.rgb = tsnow;
}
else {
gl_FragColor.rgb = mixBetween(gl_FragColor.rgb, tsnow, height, snowline_low, snowline_high);
}
}
}
}
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