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| − | == Custom shader parameters == |
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You can define and use own shader parameters like this: |
You can define and use own shader parameters like this: |
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==== '''You can also modify the parameters dynamically in you code:''' ==== |
==== '''You can also modify the parameters dynamically in you code:''' ==== |
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materialSkySphere->SetShaderParameter("SunDir",Vector3(0,1,0)); |
materialSkySphere->SetShaderParameter("SunDir",Vector3(0,1,0)); |
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| − | == Expand default terrain material to 4 textures using alpha channel == |
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| − | It's possible to also use the alpha channel as a color weight to get an additional texture for the terrain (or something else). (Using alpha/transparency makes drawing (at least in Gimp) difficult, see the next section for a better editable improvement with six colors&textures) |
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| − | |||
| − | Add another texture to the terrain material "Data/Materials/Terrain.xml" like: |
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| − | <material> |
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| − | <technique name="Techniques/TerrainBlend.xml" /> |
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| − | <texture unit="0" name="Textures/TerrainWeights.png" /> |
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| − | <texture unit="1" name="Textures/TerrainDetail1.dds" /> |
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| − | <texture unit="2" name="Textures/TerrainDetail2.dds" /> |
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| − | <texture unit="3" name="Textures/TerrainDetail3.dds" /> |
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| − | <texture unit="4" name="Textures/StoneDiffuse.dds" /> |
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| − | <parameter name="MatSpecColor" value="0.5 0.5 0.5 16" /> |
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| − | <parameter name="DetailTiling" value="16 16" /> |
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| − | </material> |
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| − | For OpenGL: Change the "CoreData/Shaders/GLSL/TerrainBlend.glsl" to additionally use the alpha channel: |
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| − | ... |
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| − | uniform sampler2D sWeightMap0; |
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| − | uniform sampler2D sDetailMap1; |
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| − | uniform sampler2D sDetailMap2; |
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| − | uniform sampler2D sDetailMap3; |
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| − | uniform sampler2D sDetailMap4; // <- added |
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| − | ... |
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| − | void PS() |
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| − | { |
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| − | // Get material diffuse albedo |
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| − | vec4 weights = texture2D(sWeightMap0, vTexCoord).rgba; // <- changed |
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| − | weights.a=1.0-weights.a; // <- added. Alpha should be weight in reverse (easier editing) |
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| − | // with 0 (fully transparent) being full weight. |
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| − | float sumWeights = weights.r + weights.g + weights.b + weights.a; // <- changed |
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| − | weights /= sumWeights; |
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| − | vec4 diffColor = cMatDiffColor * ( |
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| − | weights.r * texture2D(sDetailMap1, vDetailTexCoord) + |
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| − | weights.g * texture2D(sDetailMap2, vDetailTexCoord) + |
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| − | weights.b * texture2D(sDetailMap3, vDetailTexCoord) + // <- changed |
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| − | weights.a * texture2D(sDetailMap4, vDetailTexCoord) // <- added |
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| − | ); |
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| − | ... |
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| − | If you want to use DirectX, also change the HLSL accordingly. |
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| − | Use another splatting image (watch out for high red/green/blue values inside the alpha, it should be black with high alpha). My texture weight image and the result look like this: |
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| − | [[File:Rgba terrain.jpg|centre|thumb|730x730px]] |
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Revision as of 23:38, 25 May 2015
You can define and use own shader parameters like this:
Define the parameter in the material.xml:
<material>
<technique name="Techniques/skysphere.xml" />
<parameter name="SunDir" value="0.64 0.64 0.64"/>
<parameter name="SkyColor" value="0.9 0.5 0.5 1" />
</material>
Here I'm adding a Vector3/vec3 called SunDir and a RGBA color called SkyColor. Hint: there is no difference between RGB colors and Vector3/vec3 or between RGBA colors and Vector4/vec4, both are types with 3 respectively 4 floats.
In the Shader (here GLSL):
// at the top above and outside all functions:
uniform vec3 cSunDir;
uniform vec4 cSkyColor;
...
void PS() // the parameters can also be used in the vertex shader (VS())
{
float sun_intensity=clamp(dot(vNormal,cSunDir),0.0,1.0); // calculate a float with the dot product of the SunDir parameter and the vertex normal
gl_FragColor=cSunColor*sun_intensity; // multiplying a vec4 / RGBA-Color with a float
}
In shaders the parameter names need to be preceded with a 'c'. See http://urho3d.github.io/documentation/1.32/_shaders.html.
See http://en.wikibooks.org/wiki/GLSL_Programming/Vector_and_Matrix_Operations for an explanation of some of the shader functions.
You can also modify the parameters dynamically in you code:
materialSkySphere->SetShaderParameter("SunDir",Vector3(0,1,0));