shader_type spatial;
// Development shader used to debug or help authoring.
uniform sampler2D u_terrain_heightmap;
uniform sampler2D u_terrain_normalmap;
uniform sampler2D u_terrain_colormap;
uniform sampler2D u_map; // This map will control color
uniform mat4 u_terrain_inverse_transform;
uniform mat3 u_terrain_normal_basis;
varying float v_hole;
vec3 unpack_normal(vec4 rgba) {
return rgba.xzy * 2.0 - vec3(1.0);
}
void vertex() {
vec4 wpos = WORLD_MATRIX * vec4(VERTEX, 1);
vec2 cell_coords = (u_terrain_inverse_transform * wpos).xz;
// Must add a half-offset so that we sample the center of pixels,
// otherwise bilinear filtering of the textures will give us mixed results (#183)
cell_coords += vec2(0.5);
// Normalized UV
UV = cell_coords / vec2(textureSize(u_terrain_heightmap, 0));
// Height displacement
float h = texture(u_terrain_heightmap, UV).r;
VERTEX.y = h;
wpos.y = h;
// Putting this in vertex saves 2 fetches from the fragment shader,
// which is good for performance at a negligible quality cost,
// provided that geometry is a regular grid that decimates with LOD.
// (downside is LOD will also decimate tint and splat, but it's not bad overall)
vec4 tint = texture(u_terrain_colormap, UV);
v_hole = tint.a;
// Need to use u_terrain_normal_basis to handle scaling.
// For some reason I also had to invert Z when sampling terrain normals... not sure why
NORMAL = u_terrain_normal_basis
* (unpack_normal(texture(u_terrain_normalmap, UV)) * vec3(1, 1, -1));
}
void fragment() {
if (v_hole < 0.5) {
// TODO Add option to use vertex discarding instead, using NaNs
discard;
}
vec3 terrain_normal_world =
u_terrain_normal_basis * (unpack_normal(texture(u_terrain_normalmap, UV)) * vec3(1,1,-1));
terrain_normal_world = normalize(terrain_normal_world);
vec3 normal = terrain_normal_world;
vec4 value = texture(u_map, UV);
// TODO Blend toward checker pattern to show the alpha channel
ALBEDO = value.rgb;
ROUGHNESS = 0.5;
NORMAL = (INV_CAMERA_MATRIX * (vec4(normal, 0.0))).xyz;
}