public void Emission_ShouldBeOneSided()
{
var mesh = new Mesh(
new Vector3[] {
new Vector3(-1, 10, -1),
new Vector3(1, 10, -1),
new Vector3(1, 10, 1),
new Vector3(-1, 10, 1)
}, new int[] {
0, 1, 2,
0, 2, 3
},
shadingNormals: new Vector3[] {
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0)
}
);
var emitter = new DiffuseEmitter(mesh, RgbColor.White);
var dummyHit = new SurfacePoint {
Mesh = mesh
};
var r1 = emitter.EmittedRadiance(dummyHit, new Vector3(0, 1, 1));
var r2 = emitter.EmittedRadiance(dummyHit, new Vector3(0, -1, 1));
Assert.True(r1.R > 0);
Assert.Equal(0, r2.R);
}
public void EmittedRays_SampleInverse()
{
var mesh = new Mesh(
new Vector3[] {
new Vector3(-1, 10, -1),
new Vector3(1, 10, -1),
new Vector3(1, 10, 1),
new Vector3(-1, 10, 1)
}, new int[] {
0, 1, 2,
0, 2, 3
},
shadingNormals: new Vector3[] {
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0)
}
);
var emitter = new DiffuseEmitter(mesh, RgbColor.White);
var sample = emitter.SampleRay(new Vector2(0.3f, 0.8f), new Vector2(0.56f, 0.03f));
var(posP, dirP) = emitter.SampleRayInverse(sample.Point, sample.Direction);
Assert.Equal(0.3f, posP.X, 3);
Assert.Equal(0.8f, posP.Y, 3);
Assert.Equal(0.56f, dirP.X, 3);
Assert.Equal(0.03f, dirP.Y, 3);
}
public void EmittedRays_Sidedness_ShouldBeNegative()
{
var mesh = new Mesh(
new Vector3[] {
new Vector3(-1, 10, -1),
new Vector3(1, 10, -1),
new Vector3(1, 10, 1),
new Vector3(-1, 10, 1)
}, new int[] {
0, 1, 2,
0, 2, 3
},
shadingNormals: new Vector3[] {
new Vector3(0, -1, 0),
new Vector3(0, -1, 0),
new Vector3(0, -1, 0),
new Vector3(0, -1, 0)
}
);
var emitter = new DiffuseEmitter(mesh, RgbColor.White);
var sample = emitter.SampleRay(new Vector2(0.3f, 0.8f), new Vector2(0.56f, 0.03f));
Assert.True(sample.Direction.Y < 0);
}
public void EmittedRays_Pdf_ShouldBeCosHemisphere()
{
var mesh = new Mesh(
new Vector3[] {
new Vector3(-1, 10, -1),
new Vector3(1, 10, -1),
new Vector3(1, 10, 1),
new Vector3(-1, 10, 1)
}, new int[] {
0, 1, 2,
0, 2, 3
},
shadingNormals: new Vector3[] {
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0)
}
);
var emitter = new DiffuseEmitter(mesh, RgbColor.White);
var sample = emitter.SampleRay(new Vector2(0.3f, 0.8f), new Vector2(0.56f, 0.03f));
float c = Vector3.Dot(sample.Direction, new Vector3(0, 1, 0));
Assert.Equal(0.25f * c / MathF.PI, sample.Pdf);
}
public void EmittedRays_Pdf_ShouldBeOneSided()
{
var mesh = new Mesh(
new Vector3[] {
new Vector3(-1, 10, -1),
new Vector3(1, 10, -1),
new Vector3(1, 10, 1),
new Vector3(-1, 10, 1)
}, new int[] {
0, 1, 2,
0, 2, 3
},
shadingNormals: new Vector3[] {
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0)
}
);
var emitter = new DiffuseEmitter(mesh, RgbColor.White);
var dummyHit = new SurfacePoint {
Mesh = mesh
};
var p1 = emitter.PdfRay(dummyHit, new Vector3(0, 1, 1));
var p2 = emitter.PdfRay(dummyHit, new Vector3(0, -1, 1));
Assert.True(p1 > 0);
Assert.Equal(0, p2);
}
public void EmittedRays_ShouldHaveOffset()
{
var mesh = new Mesh(
new Vector3[] {
new Vector3(-1, 10, -1),
new Vector3(1, 10, -1),
new Vector3(1, 10, 1),
new Vector3(-1, 10, 1)
}, new int[] {
0, 1, 2,
0, 2, 3
}
);
var emitter = new DiffuseEmitter(mesh, RgbColor.White);
var sample = emitter.SampleRay(new Vector2(0.3f, 0.8f), new Vector2(0.56f, 0.03f));
Assert.True(sample.Point.ErrorOffset > 0);
}
public void EmittedRays_Weight_ShouldBeRadianceOverPdf()
{
var mesh = new Mesh(
new Vector3[] {
new Vector3(-1, 10, -1),
new Vector3(1, 10, -1),
new Vector3(1, 10, 1),
new Vector3(-1, 10, 1)
}, new int[] {
0, 1, 2,
0, 2, 3
},
shadingNormals: new Vector3[] {
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0),
new Vector3(0, 1, 0)
}
);
var emitter = new DiffuseEmitter(mesh, RgbColor.White);
var sample = emitter.SampleRay(new Vector2(0.3f, 0.8f), new Vector2(0.56f, 0.03f));
float c = Vector3.Dot(sample.Direction, new Vector3(0, 1, 0));
float expectedPdf = 0.25f * c / MathF.PI;
Assert.Equal(expectedPdf, sample.Pdf);
var expectedWeight =
emitter.EmittedRadiance(sample.Point, sample.Direction) * c
/ expectedPdf;
Assert.Equal(expectedWeight.R, sample.Weight.R);
Assert.Equal(expectedWeight.G, sample.Weight.G);
Assert.Equal(expectedWeight.B, sample.Weight.B);
}
public override Scene MakeScene()
{
var scene = new Scene();
// Create the camera
var worldToCamera = Matrix4x4.CreateLookAt(-1 * Vector3.UnitZ,
Vector3.Zero,
Vector3.UnitY);
scene.Camera = new PerspectiveCamera(worldToCamera, 45);
// Create the two transmissive planes in-between
// first plane
var mesh = new Mesh(new Vector3[] {
new Vector3(-1, -1, 0),
new Vector3(1, -1, 0),
new Vector3(1, 1, 0),
new Vector3(-1, 1, 0),
}, new int[] {
0, 1, 2,
0, 2, 3,
});
mesh.Material = new GenericMaterial(new GenericMaterial.Parameters {
BaseColor = new TextureRgb(RgbColor.White),
Roughness = new TextureMono(0.5f),
SpecularTransmittance = 1,
Thin = true,
DiffuseTransmittance = 1,
});
scene.Meshes.Add(mesh);
// second plane
mesh = new Mesh(new Vector3[] {
new Vector3(-1, -1, 1),
new Vector3(1, -1, 1),
new Vector3(1, 1, 1),
new Vector3(-1, 1, 1),
}, new int[] {
0, 1, 2,
0, 2, 3,
});
mesh.Material = new GenericMaterial(new GenericMaterial.Parameters {
BaseColor = new TextureRgb(RgbColor.White),
Roughness = new TextureMono(0.5f),
Thin = true,
DiffuseTransmittance = 1,
});
scene.Meshes.Add(mesh);
// Create the light source
var lightArea = 0.1f;
var pos = MathF.Sqrt(lightArea) / 2;
var lightMesh = new Mesh(new Vector3[] {
new Vector3(-pos, -pos, 1 + 10),
new Vector3(pos, -pos, 1 + 10),
new Vector3(pos, pos, 1 + 10),
new Vector3(-pos, pos, 1 + 10),
}, new int[] {
0, 1, 2,
0, 2, 3,
}, new Vector3[] {
-Vector3.UnitZ,
-Vector3.UnitZ,
-Vector3.UnitZ,
-Vector3.UnitZ,
});
lightMesh.Material = new DiffuseMaterial(new DiffuseMaterial.Parameters {
BaseColor = new TextureRgb(RgbColor.Black)
});
scene.Meshes.Add(lightMesh);
var lightPower = 500;
var radiance = lightPower / (MathF.PI * lightArea);
var emitter = new DiffuseEmitter(lightMesh, RgbColor.White * radiance);
scene.Emitters.Add(emitter);
scene.FrameBuffer = new FrameBuffer(512, 512, "");
scene.Prepare();
return(scene);
}
/// <summary>
/// Loads a mesh from a .fbx file and adds it to the given scene. Technically, this would also work
/// for any other file format supported by Assimp, but we are doing some .fbx specific hacks to achieve
/// the correct scale and other conventions.
/// </summary>
/// <param name="filename">Path to an existing .fbx mesh</param>
/// <param name="scene">The scene to which the mesh should be added</param>
/// <param name="materialOverride">
/// Materials from the .fbx with a name matching one of the keys in this dictionary will be
/// replaced by the corresponding dictionary entry
/// </param>
/// <param name="emissionOverride">
/// If a material name is a key in this dictionary, all meshes with that material will be
/// converted to diffuse emitters. The value from the dictionary determines their emitted radiance.
/// </param>
public static void AddToScene(string filename, Scene scene, Dictionary <string, Material> materialOverride,
Dictionary <string, RgbColor> emissionOverride = null)
{
// Load the file with some basic post-processing
Assimp.AssimpContext context = new();
var assimpScene = context.ImportFile(filename,
Assimp.PostProcessSteps.Triangulate | Assimp.PostProcessSteps.PreTransformVertices);
// Add all meshes to the scene
foreach (var m in assimpScene.Meshes)
{
var material = assimpScene.Materials[m.MaterialIndex];
string materialName = material.Name;
Vector3[] vertices = new Vector3[m.VertexCount];
for (int i = 0; i < m.VertexCount; ++i)
{
vertices[i] = new Vector3(-m.Vertices[i].X, m.Vertices[i].Z, m.Vertices[i].Y) * 0.01f;
}
Vector3[] normals = null;
if (m.HasNormals)
{
normals = new Vector3[m.VertexCount];
for (int i = 0; i < m.VertexCount; ++i)
{
normals[i] = new(-m.Normals[i].X, m.Normals[i].Z, m.Normals[i].Y);
}
}
// We currently only support a single uv channel
Vector2[] texCoords = null;
if (m.HasTextureCoords(0))
{
texCoords = new Vector2[m.VertexCount];
var texCoordChannel = m.TextureCoordinateChannels[0];
for (int i = 0; i < m.VertexCount; ++i)
{
texCoords[i] = new(texCoordChannel[i].X, 1 - texCoordChannel[i].Y);
}
}
if (m.TextureCoordinateChannelCount > 1)
{
Logger.Log($"Ignoring additional uv channels in mesh \"{m.Name}\" read from \"{filename}\"",
Verbosity.Warning);
}
// If the material is not overridden by json, we load the diffuse color, or set an error color
Material mat;
if (materialOverride.ContainsKey(materialName))
{
mat = materialOverride[materialName];
}
else if (material.HasColorDiffuse)
{
var c = material.ColorDiffuse;
mat = new DiffuseMaterial(new() {
BaseColor = new Image.TextureRgb(new RgbColor(c.R, c.G, c.B))
});
}
else
{
mat = new DiffuseMaterial(new() {
BaseColor = new Image.TextureRgb(new RgbColor(1, 0, 1))
});
}
Mesh mesh = new(vertices, m.GetIndices(), normals, texCoords) {
Material = mat
};
scene.Meshes.Add(mesh);
// Create an emitter if requested
if (emissionOverride != null && emissionOverride.TryGetValue(materialName, out var emission))
{
var emitter = new DiffuseEmitter(mesh, emission);
scene.Emitters.Add(emitter);
}
}
}
}