61 lines
2.0 KiB
Markdown
61 lines
2.0 KiB
Markdown
# Normals
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## Default Normals
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Even if you assign normal textures to your Edge Material, the normals will look wrong.
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For example, consider the following image:
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The normals in the image clearly don't line up with where the light is actually coming from.
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## Encoding Normal data in the canvas_item Vertex Shader Color Parameter
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As SmartShape renders the edges, the textures and their normal textures are also rotated.
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This will result in incorrect normals.
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To solve this, we can use a shader to correctly calculate the normals.
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The tricky part lies in how few ways there are to pass data to a canvasItem shader on a per-vertex basis.
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See here for the full list:
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https://docs.godotengine.org/en/stable/tutorials/shading/shading_reference/canvas_item_shader.html#doc-canvas-item-shader
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Fortunately, the COLOR parameter can be used for this purpose.
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The COLOR ENCODING paramter of an Edge Material can be used to choose what data is encoded in the
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Vertex Shader's Color Parameter.
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If we set the COLOR ENCODING value to "Normals", we get this:
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Ok, so now the normals still look wrong, but the colors look wrong too. Great.
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There is one final step before our normals will be correct. We need to decode the normal data in a shader.
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## Writing a Shader
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You'll want to assign a new shader to the Edge Material's material property.
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This shader will determine how each edge is rendered.
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Here's a sample shader to decode our normal data and set our actual color to that of our diffuse texture:
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```glsl
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shader_type canvas_item;
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varying mat2 NORMAL_MATRIX;
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void vertex() {
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NORMAL_MATRIX = mat2(COLOR.rg, COLOR.ba)*2.0 - mat2(vec2(1.0), vec2(1.0));
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}
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void fragment() {
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NORMAL.xy = NORMAL_MATRIX*NORMAL.xy;
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COLOR = texture(TEXTURE, UV);
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}
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```
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After assigning this shader the the Edge Material's material property, our normals finally look right:
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