50 lines
1.6 KiB
GLSL
50 lines
1.6 KiB
GLSL
shader_type canvas_item;
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render_mode blend_disabled;
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uniform sampler2D u_brush_texture;
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uniform float u_factor = 1.0;
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uniform vec4 u_splat = vec4(1.0, 0.0, 0.0, 0.0);
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uniform sampler2D u_heightmap;
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uniform float u_normal_min_y = 0.0;
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uniform float u_normal_max_y = 1.0;
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//uniform float u_normal_falloff = 0.0;
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vec3 get_normal(sampler2D heightmap, vec2 pos) {
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vec2 ps = vec2(1.0) / vec2(textureSize(heightmap, 0));
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float hnx = texture(heightmap, pos + vec2(-ps.x, 0.0)).r;
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float hpx = texture(heightmap, pos + vec2(ps.x, 0.0)).r;
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float hny = texture(heightmap, pos + vec2(0.0, -ps.y)).r;
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float hpy = texture(heightmap, pos + vec2(0.0, ps.y)).r;
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return normalize(vec3(hnx - hpx, 2.0, hpy - hny));
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}
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// Limits painting based on the slope, with a bit of falloff
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float apply_slope_limit(float brush_value, vec3 normal, float normal_min_y, float normal_max_y) {
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float normal_falloff = 0.2;
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// If an edge is at min/max, make sure it won't be affected by falloff
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normal_min_y = normal_min_y <= 0.0 ? -2.0 : normal_min_y;
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normal_max_y = normal_max_y >= 1.0 ? 2.0 : normal_max_y;
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brush_value *= 1.0 - smoothstep(
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normal_max_y - normal_falloff,
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normal_max_y + normal_falloff, normal.y);
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brush_value *= smoothstep(
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normal_min_y - normal_falloff,
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normal_min_y + normal_falloff, normal.y);
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return brush_value;
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}
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void fragment() {
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float brush_value = texture(u_brush_texture, SCREEN_UV).r * u_factor;
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vec3 normal = get_normal(u_heightmap, UV);
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brush_value = apply_slope_limit(brush_value, normal, u_normal_min_y, u_normal_max_y);
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vec4 src_splat = texture(TEXTURE, UV);
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vec4 s = mix(src_splat, u_splat, brush_value);
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s = s / (s.r + s.g + s.b + s.a);
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COLOR = s;
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}
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