62 lines
2 KiB
Text
62 lines
2 KiB
Text
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shader_type spatial;
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// This is a very simple shader for a low-poly coloured visual, without textures
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uniform sampler2D u_terrain_heightmap;
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uniform sampler2D u_terrain_normalmap;
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// I had to remove `hint_albedo` from colormap because it makes sRGB conversion kick in,
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// which snowballs to black when doing GPU painting on that texture...
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uniform sampler2D u_terrain_colormap;// : hint_albedo;
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uniform mat4 u_terrain_inverse_transform;
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uniform mat3 u_terrain_normal_basis;
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varying flat vec4 v_tint;
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vec3 unpack_normal(vec4 rgba) {
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vec3 n = rgba.xzy * 2.0 - vec3(1.0);
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// Had to negate Z because it comes from Y in the normal map,
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// and OpenGL-style normal maps are Y-up.
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n.z *= -1.0;
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return n;
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}
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void vertex() {
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vec2 cell_coords = (u_terrain_inverse_transform * WORLD_MATRIX * vec4(VERTEX, 1)).xz;
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// Must add a half-offset so that we sample the center of pixels,
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// otherwise bilinear filtering of the textures will give us mixed results (#183)
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cell_coords += vec2(0.5);
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// Normalized UV
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UV = cell_coords / vec2(textureSize(u_terrain_heightmap, 0));
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// Height displacement
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float h = texture(u_terrain_heightmap, UV).r;
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VERTEX.y = h;
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// Putting this in vertex saves 2 fetches from the fragment shader,
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// which is good for performance at a negligible quality cost,
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// provided that geometry is a regular grid that decimates with LOD.
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// (downside is LOD will also decimate tint and splat, but it's not bad overall)
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v_tint = texture(u_terrain_colormap, UV);
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// Need to use u_terrain_normal_basis to handle scaling.
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NORMAL = u_terrain_normal_basis * unpack_normal(texture(u_terrain_normalmap, UV));
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}
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void fragment() {
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if (v_tint.a < 0.5) {
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// TODO Add option to use vertex discarding instead, using NaNs
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discard;
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}
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vec3 terrain_normal_world =
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u_terrain_normal_basis * unpack_normal(texture(u_terrain_normalmap, UV));
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terrain_normal_world = normalize(terrain_normal_world);
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ALBEDO = v_tint.rgb;
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ROUGHNESS = 1.0;
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NORMAL = normalize(cross(dFdx(VERTEX), dFdy(VERTEX)));
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}
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