AnimationInterface anim("DDoSim.xml");
ns3::AnimationInterface::SetConstantPosition(nodes.Get(0), 0, 0);
ns3::AnimationInterface::SetConstantPosition(nodes.Get(1), 10, 10);
ns3::AnimationInterface::SetConstantPosition(nodes.Get(2), 23, 10);
anim.UpdateNodeColor(nodes.Get(0), 0, 0, 255);
uint32_t x_pos = 0;
for (int l = 0; l < NUMBER_OF_BOTS; ++l)
{
ns3::AnimationInterface::SetConstantPosition(botNodes.Get(l), x_pos++, 30);
}
By default all the packets in the simulation are shown in blue color.
I want the packet originating from node 0 in the simulation to be shown with different color than originating from botnodes, show that it can be easily seen which packets are from node0 and which are from botNodes.
Is there any way I can achieve this?
There is no way you can do so. You can only change the color of nodes, but not packets.
Related
In CImg, I have split an RGBA image apart into multiple single-channel images, with code like:
CImg<unsigned char> input("foo.png");
CImg<unsigned char> r = input.get_channel(0), g = input.get_channel(1), b = input.get_channel(2), a = input.get_channel(3);
Then I try to swizzle the channel order:
CImg<unsigned char> output(input.width(), input.height(), 1, input.channels());
output.channel(0) = g;
output.channel(1) = b;
output.channel(2) = r;
output.channel(3) = a;
When I save the image out, however, it turns out grayscale, apparently based on the alpha channel value; for example, this input:
becomes this output:
How do I specify the image color format so that CImg saves into the correct color space?
Simply copying a channel does not work like that; a better approach is to copy the pixel data with std::copy:
std::copy(g.begin(), g.end(), &output.atX(0, 0, 0, 0));
std::copy(b.begin(), b.end(), &output.atX(0, 0, 0, 1));
std::copy(r.begin(), r.end(), &output.atX(0, 0, 0, 2));
std::copy(a.begin(), a.end(), &output.atX(0, 0, 0, 3));
This results in an output image like:
I wanted to calculate the brightness of an UintList image. The image I used are picked from my phone (Using image_picker plugin in flutter). I tried a for loop on every value of this list and did this:
int r = 0, b = 0, g = 0, count = 0;
for (int value in imageBytesList) {
/// The red channel of this color in an 8 bit value.
int red = (0x00ff0000 & value) >> 16;
/// The blue channel of this color in an 8 bit value.
int blue = (0x0000ff00 & value) >> 8;
/// The green channel of this color in an 8 bit value.
int green = (0x000000ff & value) >> 0;
r += red;
b += blue;
g += green;
count++;
}
double result = (r + b + g) / (count * 3);
I know that the result should represent a brightness level between 0 and 255, where 0 = totally black and 255 = totally bright. but, what I get are really weird values like 0.0016887266175341332. What calculation mistakes am I making? (I know my method is gravely wrong but I wasn't able to find a way).
The flutter image widget does convert this Uint8List from memory to an Image with correct height & width using Image.memory() constructor. What is the logic behind it?
I am using Cairo and would like to render one color component at a time. For example, if I render a set of blue rectangles and then render a set of red rectangles, I want where they overlap to be purple rather than red.
Using set_source_rgb(ctx, 0.0, 1.0, 0.0) doesn't work, because it will overwrite the other channels with zeros. Using transparency doesn't work either, as it equally effects all channels. I would like a way to only render to one channel.
Is that possible? Thank you.
Use CAIRO_OPERATOR_ADD instead of CAIRO_OPERATOR_OVER (the default):
#include <cairo.h>
int main() {
cairo_surface_t *s = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 20, 20);
cairo_t *cr = cairo_create(s);
cairo_set_operator(cr, CAIRO_OPERATOR_ADD);
/* Render blue */
cairo_set_source_rgb(cr, 0, 0, 1);
cairo_rectangle(cr, 0, 0, 15, 15);
cairo_fill(cr);
/* Render red */
cairo_set_source_rgb(cr, 1, 0, 0);
cairo_rectangle(cr, 5, 5, 15, 15);
cairo_fill(cr);
cairo_surface_write_to_png(s, "out.png");
cairo_destroy(cr);
cairo_surface_destroy(s);
return 0;
}
I am working on GWT canvas which is similar to HTML 5 canvas. My goal is to get the pixel color from the canvas. I found one way to do this by using CanvasPixelArray which store the image data. Image data store the pixel information. I am using following code to get the pixel color from canvas :
CanvasPixelArray imageData = canvas.getRendererCanvas().getContext2d().getImageData(0, 0, canvas.getWidth(), canvas.getHeight()).getData();
int length = imageData.getLength() / 4;
int index = 0, r, g, b, a;
for (int i = 0; i < length; i++) {
index = 4 * i;
r = imageData.get(index); //red
g = imageData.get(++index); //green
b = imageData.get(++index); //blue
a = imageData.get(++index); //alpha
if (r == 255 || g == 255 || b == 255) { // pixel is white
System.out.println(r+","+g+","+b+","+a);
}
}
But the major problem is that it's working too slow and down the performance. This is the main issue otherwise above code working fine.
So what is the best way performance wise to get the color information from canvas.
Any help is highly appreciated. Thank you.
I have a project in which i need make a matlab based simulation of a robotic arm.
img http://img845.imageshack.us/img845/4512/l5mx.png
The first part sits in the origin, and can rotate around the Z axis in the world coordinate system. This joint is called joint1. The next joint, joint2 is displaced 0.8m in the Z direction of the coordinate system of part 1. It will rotate around the Y axis of the coordinate system of part2. Joint3 is displaced 0.6m in the Z direction of the csystem of part2. It will rotate around the y axis of the csystem of part3. The end of part3 is displaced 0.7m in the Z direction of csystem of part3.
Now, lets try to do some matrices of this. I'm quite sure i'm doing something wrong with these. The coordinates will be in homogenous form, so v = [v,1].
T_Wto1 = [cos(alpha(1)), -sin(alpha(1)), 0 , 0;
sin(alpha(1)), cos(alpha(1)), 0 , 0;
0, 0, 1 , 0.8;
0, 0, 0, 1];
T_1to2 = [cos(alpha(2)), 0, sin(alpha(2)), 0;
0, 1, 0, 0;
-sin(alpha(2)), 0, cos(alpha(2)), 0.6;
0, 0, 0, 1];
T_2to3 = [cos(alpha(3)), 0, sin(alpha(3)), 0;
0, 1, 0, 0;
-sin(alpha(3)), 0, cos(alpha(3)), 0.7;
0, 0, 0, 1];
For alpha(1) = 0, alpha(2) = alpha(3) = pi/2
First of all. If i use p1 = T_Wto1*[0,0,0,1]', i get [0,0,0.8,1]', so far so good. Then, T_1to2*[0,0,0.8,1]' gives [0.8,0,0.6,1]' (it is now displaced 0.8 in the X direction, which is really 0.8 in the Z direction, because of the rotation). Now, say that i want to transform this back to world coordinates. It should say [0.6,0,0.8], but i'm unsure on how to do that. If you just take the inverse of the matrix T_Wto2 (a product of T_Wto1 and T_1to2), you just get the origin [0,0,0,1] back. What are you supposed to do to make it back into world coordinates again?
Also, are the transformation matrices correct?