1 files changed, 63 insertions, 0 deletions
diff --git a/game/addons/zylann.hterrain/shaders/low_poly.gdshader b/game/addons/zylann.hterrain/shaders/low_poly.gdshader
new file mode 100644
index 0000000..6c98104
--- /dev/null
+++ b/game/addons/zylann.hterrain/shaders/low_poly.gdshader
@@ -0,0 +1,63 @@
+shader_type spatial;
+
+// This is a very simple shader for a low-poly coloured visual, without textures
+
+#include "include/heightmap.gdshaderinc"
+
+uniform sampler2D u_terrain_heightmap;
+uniform sampler2D u_terrain_normalmap;
+// I had to remove `hint_albedo` from colormap in Godot 3 because it makes sRGB conversion kick in,
+// which snowballs to black when doing GPU painting on that texture...
+uniform sampler2D u_terrain_colormap;// : hint_albedo;
+uniform mat4 u_terrain_inverse_transform;
+uniform mat3 u_terrain_normal_basis;
+
+varying flat vec4 v_tint;
+
+
+vec3 unpack_normal(vec4 rgba) {
+	vec3 n = rgba.xzy * 2.0 - vec3(1.0);
+	// Had to negate Z because it comes from Y in the normal map,
+	// and OpenGL-style normal maps are Y-up.
+	n.z *= -1.0;
+	return n;
+}
+
+void vertex() {
+	vec2 cell_coords = (u_terrain_inverse_transform * MODEL_MATRIX * vec4(VERTEX, 1)).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 = sample_heightmap(u_terrain_heightmap, UV);
+	VERTEX.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)
+	v_tint = texture(u_terrain_colormap, UV);
+	
+	// Need to use u_terrain_normal_basis to handle scaling.
+	NORMAL = u_terrain_normal_basis * unpack_normal(texture(u_terrain_normalmap, UV));
+}
+
+void fragment() {
+	if (v_tint.a < 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));
+	terrain_normal_world = normalize(terrain_normal_world);
+	
+	ALBEDO = v_tint.rgb;
+	ROUGHNESS = 1.0;
+	NORMAL = normalize(cross(dFdy(VERTEX), dFdx(VERTEX)));
+}
+