feat: implemented terrain shader

project/assets/materials/terrain_material.tres

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+[gd_resource type="ShaderMaterial" load_steps=8 format=3 uid="uid://8j7uyk0vnllg"]
+
+[ext_resource type="Shader" uid="uid://dsbxpdveoilep" path="res://assets/shaders/terrain.gdshader" id="1_ho7uc"]
+
+[sub_resource type="Gradient" id="Gradient_ho7uc"]
+colors = PackedColorArray(0.141108, 0.450995, 0.106614, 1, 0.259524, 0.499032, 0.232917, 1)
+
+[sub_resource type="FastNoiseLite" id="FastNoiseLite_mqhx5"]
+
+[sub_resource type="NoiseTexture2D" id="NoiseTexture2D_waqik"]
+color_ramp = SubResource("Gradient_ho7uc")
+noise = SubResource("FastNoiseLite_mqhx5")
+
+[sub_resource type="Gradient" id="Gradient_mqhx5"]
+
+[sub_resource type="FastNoiseLite" id="FastNoiseLite_waqik"]
+
+[sub_resource type="NoiseTexture2D" id="NoiseTexture2D_oj3sr"]
+color_ramp = SubResource("Gradient_mqhx5")
+noise = SubResource("FastNoiseLite_waqik")
+
+[resource]
+render_priority = 0
+shader = ExtResource("1_ho7uc")
+shader_parameter/floor_1_albedo = SubResource("NoiseTexture2D_waqik")
+shader_parameter/floor_1_roughness = 1.0
+shader_parameter/floor_1_tiling = 500.0
+shader_parameter/floor_1_specular = 0.0
+shader_parameter/floor_1_metallic = 0.5
+shader_parameter/floor_2_roughness = 0.7
+shader_parameter/floor_2_tiling = 500.0
+shader_parameter/floor_2_specular = 0.5
+shader_parameter/floor_2_metallic = 0.5
+shader_parameter/floor_3_roughness = 0.7
+shader_parameter/floor_3_tiling = 500.0
+shader_parameter/floor_3_specular = 0.5
+shader_parameter/floor_3_metallic = 0.5
+shader_parameter/region_blending = 1.0
+shader_parameter/slope_threshold = 0.25
+shader_parameter/slope_blend_distance = 0.0
+shader_parameter/slope_albedo = SubResource("NoiseTexture2D_oj3sr")
+shader_parameter/slope_tiling = 100.0
+shader_parameter/slope_roughness = 1.0
+shader_parameter/slope_specular = 1.0
+shader_parameter/slope_metallic = 0.5

project/assets/shaders/terrain.gdshader

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+shader_type spatial;
+render_mode blend_mix, depth_draw_opaque, diffuse_lambert, specular_schlick_ggx, skip_vertex_transform;
+
+varying vec3 var_model_normal;
+varying vec3 var_vertex_position;
+
+group_uniforms Floor1;
+uniform sampler2D floor_1_albedo : source_color, hint_default_black, filter_linear_mipmap;
+uniform sampler2D floor_1_normal : hint_normal, filter_linear_mipmap;
+uniform float floor_1_roughness = 0.7;
+uniform float floor_1_tiling = 500.0;
+uniform float floor_1_specular = 0.5;
+uniform float floor_1_metallic = 0.5;
+
+group_uniforms Floor2;
+uniform sampler2D floor_2_albedo : source_color, hint_default_black, filter_linear_mipmap;
+uniform sampler2D floor_2_normal : hint_normal, filter_linear_mipmap;
+uniform float floor_2_roughness = 0.7;
+uniform float floor_2_tiling = 500.0;
+uniform float floor_2_specular = 0.5;
+uniform float floor_2_metallic = 0.5;
+
+group_uniforms Floor3;
+uniform sampler2D floor_3_albedo : source_color, hint_default_black, filter_linear_mipmap;
+uniform sampler2D floor_3_normal : hint_normal, filter_linear_mipmap;
+uniform float floor_3_roughness = 0.7;
+uniform float floor_3_tiling = 500.0;
+uniform float floor_3_specular = 0.5;
+uniform float floor_3_metallic = 0.5;
+
+group_uniforms Regions;
+uniform sampler2D floor_region_map : hint_default_black, filter_linear_mipmap;
+uniform float region_blending : hint_range(0, 10) = 1.0;
+
+group_uniforms Slope.Textures;
+uniform sampler2D slope_albedo : source_color, hint_default_white;
+uniform sampler2D slope_normal : hint_normal, filter_linear_mipmap;
+
+uniform float slope_tiling = 100.0;
+uniform float slope_roughness = 0.7;
+uniform float slope_specular = 0.5;
+uniform float slope_metallic = 0.5;
+
+group_uniforms; group_uniforms Slope;
+uniform float slope_threshold = 0.9;
+uniform float slope_blend_distance = 0.05;
+
+void vertex() {
+	var_model_normal = NORMAL;
+	var_vertex_position = (vec4(VERTEX, 1.0) * MODEL_MATRIX).xyz;
+	VERTEX = (MODELVIEW_MATRIX * vec4(VERTEX, 1.0)).xyz;
+	NORMAL = normalize(MODELVIEW_MATRIX * vec4(NORMAL, 0.0)).xyz;
+	TANGENT = normalize(MODELVIEW_MATRIX * vec4(TANGENT, 0.0)).xyz;
+	BINORMAL = normalize(MODELVIEW_MATRIX * vec4(BINORMAL, 0.0)).xyz;
+}
+
+vec3 lerp(vec3 a, vec3 b, float t) {
+	return (1.0 - t) * a + b * t;
+}
+
+float lerpf(float a, float b, float t) {
+	return (1.0 - t) * a + b * t;
+}
+
+vec2 lerp2(vec2 a, vec2 b, float t) {
+	return (1.0 - t) * a + b * t;
+}
+
+// adapted from https://github.com/Experience-Monks/glsl-fast-gaussian-blur/blob/master/9.glsl
+vec4 sample_texture_blurred(sampler2D tex, vec2 uv) {
+	if(region_blending == 0.0) // short-circuit for zero case
+		return texture(tex, uv);
+	vec4 color = vec4(0.0);
+	vec2 resolution = vec2(textureSize(tex, 0));
+	vec2 offset_1 = vec2(1.3846153846) * region_blending;
+	vec2 offset_2 = vec2(3.2307692308) * region_blending;
+	// add weighted samples. Magic numbers are pre-computed gaussian function results
+	color += texture(tex, uv) * 0.2270270270;
+	color += texture(tex, uv + (offset_1 / resolution)) * 0.3162162162;
+	color += texture(tex, uv - (offset_1 / resolution)) * 0.3162162162;
+	color += texture(tex, uv + (offset_2 / resolution)) * 0.0702702703;
+	color += texture(tex, uv - (offset_2 / resolution)) * 0.0702702703;
+	return color;
+}
+
+void fragment() {
+	float slope_blend = clamp(slope_threshold + ((acos(abs(var_model_normal.y)) / (PI * 0.5) - slope_threshold) * 1.0/slope_blend_distance), 0.0, 1.0);
+
+	vec4 region_masks = sample_texture_blurred(floor_region_map, UV);
+	vec2 sqr_normal = normalize(var_model_normal.xz * var_model_normal.xz);
+	float biplanar_index = round(abs(sqr_normal.x));
+	vec2 slope_uv = lerp2(var_vertex_position.xy, var_vertex_position.yz, biplanar_index);
+
+	ALBEDO = texture(floor_1_albedo, UV * floor_1_tiling).xyz;
+	ALBEDO = lerp(ALBEDO, texture(floor_2_albedo, UV * floor_2_tiling).xyz, region_masks.x);
+	ALBEDO = lerp(ALBEDO, texture(floor_3_albedo, UV * floor_3_tiling).xyz, region_masks.y);
+	ALBEDO = lerp(ALBEDO, texture(slope_albedo, slope_uv * slope_tiling).xyz, slope_blend);
+	//ALBEDO = region_masks.xyz;
+
+	NORMAL_MAP = texture(floor_1_normal, UV * floor_1_tiling).xyz;
+	NORMAL_MAP = lerp(NORMAL_MAP, texture(floor_2_normal, UV * floor_2_tiling).xyz, region_masks.x);
+	NORMAL_MAP = lerp(NORMAL_MAP, texture(floor_3_normal, UV * floor_3_tiling).xyz, region_masks.y);
+	NORMAL_MAP = lerp(NORMAL_MAP, texture(slope_normal, slope_uv * slope_tiling).xyz, slope_blend);
+
+	SPECULAR = floor_1_specular;
+	SPECULAR = lerpf(SPECULAR, floor_2_specular, region_masks.x);
+	SPECULAR = lerpf(SPECULAR, floor_3_specular, region_masks.y);
+	SPECULAR = lerpf(SPECULAR, slope_specular, slope_blend);
+
+	ROUGHNESS = floor_1_roughness;
+	ROUGHNESS = lerpf(ROUGHNESS, floor_2_roughness, region_masks.x);
+	ROUGHNESS = lerpf(ROUGHNESS, floor_3_roughness, region_masks.y);
+	ROUGHNESS = lerpf(ROUGHNESS, slope_roughness, slope_blend);
+	
+	METALLIC = floor_1_metallic;
+	METALLIC = lerpf(METALLIC, floor_2_metallic, region_masks.x);
+	METALLIC = lerpf(METALLIC, floor_3_metallic, region_masks.y);
+	METALLIC = lerpf(METALLIC, slope_metallic, slope_blend);
+}

project/assets/shaders/terrain.gdshader.uid

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+uid://dsbxpdveoilep