public void DrawBeziers(int count, Position <float>[] controls, Color <float>[] colors, float[] width, Matrix4x4[] transforms)
{
Utility.Assert(controls.Length >= 3 * count && colors.Length >= count && width.Length >= count);
Utility.Assert(Mode == RenderMode.Draw);
if (count == 0)
{
return;
}
TransformMatrix[] transformMatrices = new TransformMatrix[count];
Equation[] equations = new Equation[count];
Vector4[] color = new Vector4[count];
Vertex[] vertices = new Vertex[4]
{
new Vertex()
{
Position = new Vector3(0, 0, 0)
},
new Vertex()
{
Position = new Vector3(0, 1, 0)
},
new Vertex()
{
Position = new Vector3(1, 1, 0)
},
new Vertex()
{
Position = new Vector3(1, 0, 0)
}
};
var size = new Vector2(mCanvasSize.Width, mCanvasSize.Height) * 0.5f;
for (int index = 0; index < count; index++)
{
Vector2[] points = new Vector2[]
{
new Vector2(controls[index * 3 + 0].X, controls[index * 3 + 0].Y),
new Vector2(controls[index * 3 + 1].X, controls[index * 3 + 1].Y),
new Vector2(controls[index * 3 + 2].X, controls[index * 3 + 2].Y)
};
//get bounding box(before transform) of bezier curve
var box = QuadraticBezierCurve.BoundingBox(points, width[index]);
//create transform matrix
transformMatrices[index] = new TransformMatrix()
{
World =
Matrix4x4.CreateScale(box.Max.X - box.Min.X, box.Max.Y - box.Min.Y, 1) *
Matrix4x4.CreateTranslation(box.Min.X, box.Min.Y, 0) *
Transform,
Projection = mProjection
};
//we need transform the control points to screen space
var transformMatrix = (transforms == null ? Matrix4x4.Identity : transforms[index]) * Transform * mProjection;
//transform points
for (int i = 0; i < 3; i++)
{
points[i] = (Vector2.Transform(points[i], transformMatrix) + Vector2.One) * size;
points[i].Y = mCanvasSize.Height - points[i].Y;
}
//get parameter format of bezier curve
//Q(t) = At^2 + B^t + C
var parameters = QuadraticBezierCurve.ParameterFormat(points);
var A = parameters[0];
var B = parameters[1];
var C = parameters[2];
//For point P, when any root of equation(Q'(s) * (P - Q(s)) = 0) is legal, the P is inside the curve
//The equation full-format is (-2A^2)t^3 + (-3AB)t^2 + (2AP - 2AC - B^2)t + B(P - C) = 0
//we can use Cardano formula to solve it in pixel shader.
//but we can cache some calculation for opt.
var c0 = -2 * Vector2.Dot(A, A);
var c1 = -3 * Vector2.Dot(A, B);
var c2 = -2 * Vector2.Dot(A, C) - Vector2.Dot(B, B);
var c3 = -Vector2.Dot(B, C);
equations[index] = new Equation()
{
Coefficient0 = new Vector4(c0, c1, c2, c3),
Coefficient1 = new Vector4(A.X, A.Y, B.X, B.Y),
Coefficient2 = new Vector4(C.X, C.Y, width[index] * width[index] * 0.25f, width[index] * width[index] * 0.25f)
};
color[index] = new Vector4(colors[index].Red, colors[index].Green, colors[index].Blue, colors[index].Alpha);
}
if (mColorBufferArray == null || mColorBufferArray.ElementCount != count)
{
Utility.Dispose(ref mColorBufferArray);
Utility.Dispose(ref mEquationBufferArray);
Utility.Dispose(ref mTransformBufferArray);
Utility.Dispose(ref mColorBufferArrayUsage);
Utility.Dispose(ref mEquationBufferArrayUsage);
Utility.Dispose(ref mTransformBufferArrayUsage);
mColorBufferArray = new GpuBufferArray(
Utility.SizeOf <Vector4>(),
count,
mDevice,
GpuResourceInfo.BufferArray());
mEquationBufferArray = new GpuBufferArray(
Utility.SizeOf <Equation>(),
count,
mDevice,
GpuResourceInfo.BufferArray());
mTransformBufferArray = new GpuBufferArray(
Utility.SizeOf <TransformMatrix>(),
count,
mDevice,
GpuResourceInfo.BufferArray());
mColorBufferArrayUsage = new GpuResourceUsage(mDevice, mColorBufferArray);
mEquationBufferArrayUsage = new GpuResourceUsage(mDevice, mEquationBufferArray);
mTransformBufferArrayUsage = new GpuResourceUsage(mDevice, mTransformBufferArray);
}
mColorBufferArray.Update(color);
mEquationBufferArray.Update(equations);
mTransformBufferArray.Update(transformMatrices);
mDrawVertexBuffer.Update(vertices);
//change shader we use
mDevice.SetVertexShader(mDrawBeziersVertexShader);
mDevice.SetPixelShader(mDrawBeziersPixelShader);
//set vertex buffer
mDevice.SetVertexBuffer(mDrawVertexBuffer);
mDevice.SetIndexBuffer(mDrawIndexBuffer);
//set constant buffer and resource
mDevice.SetResourceUsage(mColorBufferArrayUsage, 0);
mDevice.SetResourceUsage(mEquationBufferArrayUsage, 1);
mDevice.SetResourceUsage(mTransformBufferArrayUsage, 2);
//drwa indexed instanced
mDevice.DrawIndexedInstanced(6, count);
//reset the shader
mDevice.SetVertexShader(mDrawBezierVertexShader);
mDevice.SetPixelShader(mDrawBezierPixelShader);
}
public void DrawBezier(Position <float>[] controls, Color <float> color, float width = 2.0f)
{
Utility.Assert(controls.Length >= 3);
Utility.Assert(Mode == RenderMode.Draw);
//convert Position<T> to Vector2
Vector2[] points = new Vector2[]
{
new Vector2(controls[0].X, controls[0].Y),
new Vector2(controls[1].X, controls[1].Y),
new Vector2(controls[2].X, controls[2].Y)
};
//get bounding box(before transform) of bezier curve
var box = QuadraticBezierCurve.BoundingBox(points, width);
var vertices = new Vertex[]
{
new Vertex()
{
Position = new Vector3(box.Min.X, box.Min.Y, 0)
},
new Vertex()
{
Position = new Vector3(box.Min.X, box.Max.Y, 0)
},
new Vertex()
{
Position = new Vector3(box.Max.X, box.Max.Y, 0)
},
new Vertex()
{
Position = new Vector3(box.Max.X, box.Min.Y, 0)
}
};
for (int i = 0; i < 4; i++)
{
vertices[i].Color = new Vector4(color.Red, color.Green, color.Blue, color.Alpha);
vertices[i].TexCoord = new Vector2(width);
}
//we need transform the control points to screen space
var transformMatrix = Transform * mProjection;
var size = new Vector2(mCanvasSize.Width, mCanvasSize.Height) * 0.5f;
//transform points
for (int i = 0; i < 3; i++)
{
points[i] = (Vector2.Transform(points[i], transformMatrix) + Vector2.One) * size;
points[i].Y = mCanvasSize.Height - points[i].Y;
}
//get parameter format of bezier curve
//Q(t) = At^2 + B^t + C
var parameters = QuadraticBezierCurve.ParameterFormat(points);
var A = parameters[0];
var B = parameters[1];
var C = parameters[2];
//For point P, when any root of equation(Q'(s) * (P - Q(s)) = 0) is legal, the P is inside the curve
//The equation full-format is (-2A^2)t^3 + (-3AB)t^2 + (2AP - 2AC - B^2)t + B(P - C) = 0
//we can use Cardano formula to solve it in pixel shader.
//but we can cache some calculation for opt.
var c0 = -2 * Vector2.Dot(A, A);
var c1 = -3 * Vector2.Dot(A, B);
var c2 = -2 * Vector2.Dot(A, C) - Vector2.Dot(B, B);
var c3 = -Vector2.Dot(B, C);
var equation = new Equation()
{
Coefficient0 = new Vector4(c0, c1, c2, c3),
Coefficient1 = new Vector4(A.X, A.Y, B.X, B.Y),
Coefficient2 = new Vector4(C.X, C.Y, width * width * 0.25f, width * width * 0.25f)
};
mTransformBuffer.Update(new TransformMatrix()
{
World = Transform,
Projection = mProjection
});
mDrawVertexBuffer.Update(vertices);
mEquationBuffer.Update(equation);
mDevice.SetVertexBuffer(mDrawVertexBuffer);
mDevice.SetIndexBuffer(mDrawIndexBuffer);
mDevice.SetBuffer(mTransformBuffer, 0);
mDevice.SetBuffer(mEquationBuffer, 1);
mDevice.DrawIndexed(6);
}