open-fpsz/addons/terrain_3d/extras/minimum.gdshader
2024-04-07 14:25:59 -04:00

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// This shader is the minimum needed to allow the terrain to function.
shader_type spatial;
render_mode blend_mix,depth_draw_opaque,cull_back,diffuse_burley,specular_schlick_ggx;
// Private uniforms
uniform float _region_size = 1024.0;
uniform float _region_texel_size = 0.0009765625; // = 1/1024
uniform float _mesh_vertex_spacing = 1.0;
uniform float _mesh_vertex_density = 1.0; // = 1/_mesh_vertex_spacing
uniform int _region_map_size = 16;
uniform int _region_map[256];
uniform vec2 _region_offsets[256];
uniform sampler2DArray _height_maps : repeat_disable;
varying vec3 v_vertex; // World coordinate vertex location
////////////////////////
// Vertex
////////////////////////
// Takes in UV world space coordinates, returns ivec3 with:
// XY: (0 to _region_size) coordinates within a region
// Z: layer index used for texturearrays, -1 if not in a region
ivec3 get_region_uv(vec2 uv) {
uv *= _region_texel_size;
ivec2 pos = ivec2(floor(uv)) + (_region_map_size / 2);
int bounds = int(pos.x>=0 && pos.x<_region_map_size && pos.y>=0 && pos.y<_region_map_size);
int layer_index = _region_map[ pos.y * _region_map_size + pos.x ] * bounds - 1;
return ivec3(ivec2((uv - _region_offsets[layer_index]) * _region_size), layer_index);
}
// Takes in UV2 region space coordinates, returns vec3 with:
// XY: (0 to 1) coordinates within a region
// Z: layer index used for texturearrays, -1 if not in a region
vec3 get_region_uv2(vec2 uv) {
ivec2 pos = ivec2(floor(uv)) + (_region_map_size / 2);
int bounds = int(pos.x>=0 && pos.x<_region_map_size && pos.y>=0 && pos.y<_region_map_size);
int layer_index = _region_map[ pos.y * _region_map_size + pos.x ] * bounds - 1;
return vec3(uv - _region_offsets[layer_index], float(layer_index));
}
float get_height(vec2 uv) {
highp float height = 0.0;
vec3 region = get_region_uv2(uv);
if (region.z >= 0.) {
height = texture(_height_maps, region).r;
}
return height;
}
void vertex() {
// Get vertex of flat plane in world coordinates and set world UV
v_vertex = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
// UV coordinates in world space. Values are 0 to _region_size within regions
UV = round(v_vertex.xz * _mesh_vertex_density);
// UV coordinates in region space + texel offset. Values are 0 to 1 within regions
UV2 = (UV + vec2(0.5)) * _region_texel_size;
// Get final vertex location and save it
VERTEX.y = get_height(UV2);
v_vertex = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
}
////////////////////////
// Fragment
////////////////////////
vec3 get_normal(vec2 uv, out vec3 tangent, out vec3 binormal) {
// Get the height of the current vertex
float height = get_height(uv);
// Get the heights to the right and in front, but because of hardware
// interpolation on the edges of the heightmaps, the values are off
// causing the normal map to look weird. So, near the edges of the map
// get the heights to the left or behind instead. Hacky solution that
// reduces the artifact, but doesn't fix it entirely. See #185.
float u, v;
if(mod(uv.y*_region_size, _region_size) > _region_size-2.) {
v = get_height(uv + vec2(0, -_region_texel_size)) - height;
} else {
v = height - get_height(uv + vec2(0, _region_texel_size));
}
if(mod(uv.x*_region_size, _region_size) > _region_size-2.) {
u = get_height(uv + vec2(-_region_texel_size, 0)) - height;
} else {
u = height - get_height(uv + vec2(_region_texel_size, 0));
}
vec3 normal = vec3(u, _mesh_vertex_spacing, v);
normal = normalize(normal);
tangent = cross(normal, vec3(0, 0, 1));
binormal = cross(normal, tangent);
return normal;
}
void fragment() {
// Calculate Terrain Normals
vec3 w_tangent, w_binormal;
vec3 w_normal = get_normal(UV2, w_tangent, w_binormal);
NORMAL = mat3(VIEW_MATRIX) * w_normal;
TANGENT = mat3(VIEW_MATRIX) * w_tangent;
BINORMAL = mat3(VIEW_MATRIX) * w_binormal;
// Apply PBR
ALBEDO=vec3(.2);
}