I am trying to implement shadows into my WEBGL 2.0 Project using this tutorial
https://webgl2fundamentals.org/webgl/lessons/webgl-shadows.html
Currently I am getting really bad results like this:
Basically a ton of the terrain is being drawn in shadow that shouldn't be. The light projection is from your camera towards the direction you are looking so hypothetically you shouldn't be able to see any shdaows becuase the light projection is the same as your camera ( I am just doing this for testing until I can get this working properly)
I have everything the same as the tutorial I believe except I am using glMatrix instead of their matrix math library (shouldn't matter I would assume). Here's the thing though. I don't use a model view matrix for anything I am rendering so none of my points are on a -1,1 range. They can go out as far as -3200...ect Its just all one big terrain mesh chunked out.
I think the issue lies with how I am creating the texture matrix
textureMatrix = glMatrix.mat4.create();
glMatrix.mat4.translate(textureMatrix,textureMatrix,[0.5,0.5,0.5]);
glMatrix.mat4.scale(textureMatrix,textureMatrix,[0.5,0.5,0.5]);
glMatrix.mat4.multiply(textureMatrix,textureMatrix, projectionMatrix);
glMatrix.mat4.invert(lightMatrix,lightMatrix);
glMatrix.mat4.multiply(textureMatrix,textureMatrix, lightMatrix);
I am using the same matrix for the light projection as your normal projection, is that an issue? if anyone could help it would be greatly appreciated.
That's probably because the Y position of your light (in your example, it is much more the distance between the eye and the scene) is too big for the Z size of your shadow volume (the size of your shadow volume in the view direction.) Here if posY is inside the wireframe box :
But if you increase posY too much (i.e. your shapes get out of the shadow volume, they disappear
So you should increase the size of your shadow volume (or shrinken your scene, either way.) You cannot simulate that with the slider because they just give you the control to the two dimensions X and Y dimensions : projWidth and projHeight.
i.e. in the last code in your tutorial page, the latest parameter ("far") for example change it from 10 to 100
const lightProjectionMatrix = settings.perspective
? m4.perspective(
degToRad(settings.fieldOfView),
settings.projWidth / settings.projHeight,
0.5, // near
10) // far
: m4.orthographic(
-settings.projWidth / 2, // left
settings.projWidth / 2, // right
-settings.projHeight / 2, // bottom
settings.projHeight / 2, // top
0.5, // near
100); // far
Then you can increase posY far more :
without having your full code, it is hard to reproduce and help you. Could you not try to just inject your scene into the tutorial code ? You can bind the viewpoint with the source and orientation of the light by using the same inputs : (just adding 0.5 to X to see a bit of shadow and make sure it is properly computed.)
/*const cameraPosition = [settings.cameraX, settings.cameraY, 15];*/
const cameraPosition = [settings.posX+0.5, settings.posY, settings.posZ];
/*const target = [0, 0, 0]; */
const target = [settings.targetX, settings.targetY, settings.targetZ];
Related
I don't quite get how to pass in attribute data for rendering a sprite sheet or texture atlas while instancing. Let's assume WebGl1 (so no texture layers)
Without instancing, I have these uv coordinates to pass in:
let left = cell_x / atlas_width;
let right = (cell_x + cell_width) / atlas_width;
let top = (atlas_height - cell_y) / atlas_height;
let bottom = (atlas_height - (cell_y + cell_height)) / atlas_height;
let uvs = [left, top, left, bottom, right, top, right, bottom]
But with instancing, I don't quite get how to do that... my understanding is the attributes must be identical per-instance?
I tried to think about translating the above to shader code, like maybe a multiplier of some constant... but I couldn't quite figure it out.
I can get the left,right,top, and bottom since those only depend on the constants cell_* and atlas_*, but how do I get from knowing these corners to the actual uv output, since I don't know which vertex I'm in?
Any help is appreciated. Thanks!
Objective: There is a SCNCylinder object in my scene. I want to be able to drag one end of the cylinder and rotate the cylinder in any direction, while keeping the other end in the same position.
Currently, I am calling localRotate(by: SCNQuaternion) to first rotate the node, then calculate the position offset needed to move the cylinder so that the other end can go back to its original position.
How can I achieve the objective in one step instead of what I am doing now?
The pivot property is what you're looking for. Or, since modern SceneKit often works better / makes nicer Swift / interoperates easier with ARKit when you use SIMD types, the simdPivot property.
Note this bit in the docs:
Changing the pivot transform alters these behaviors in many useful ways. You can:
Offset the node’s contents relative to its position. For example, by setting the pivot to a translation transform you can position a node containing a sphere geometry relative to where the sphere would rest on a floor instead of relative to its center.
Move the node’s axis of rotation. For example, with a translation transform you can cause a node to revolve around a faraway point instead of rotating around its center, and with a rotation transform you can tilt the axis of rotation.
Similarly, for a cylinder, you can make its pivot a transform matrix that translates the origin by half its height, giving it an "anchor point" (for position and rotation changes) at one end instead of in the center. Something like this (untested):
let cylinder = SCNCylinder(radius: /*...*/, height: /*...*/)
let cylinderNode = SCNNode(geometry: cylinder)
cylinderNode.simdPivot = float4x4(translation: cylinder.height / 2)
extension float4x4 {
init(translation vector: float3) {
self.init(float4(1, 0, 0, 0),
float4(0, 1, 0, 0),
float4(0, 0, 1, 0),
float4(vector.x, vector.y, vector.z, 1))
}
}
More generally, whenever you're using a scene-graph / transform-hierarchy based graphics framework, any time you find yourself doing math depending on one transform (rotation, translation, etc) to affect another, it's always good to check for API that can do that math for you — because doing that kind of math is what transform hierarchy is all about.
And if there's not an API fairly specific to what you need, remember that the hierarchy itself is good for making dependent transforms. For example, if you want one node to follow a circular orbit around another, you don't need to set its position using sines and cosines... just make it the child of another node, and rotate that other node.
In this case, pivot is a convenience equivalent to using the node hierarchy. You could just as well create an intermediate node and move the cylinder within it (something like this):
let cylinder = SCNCylinder(radius: /*...*/, height: /*...*/)
let cylinderNode = SCNNode(geometry: cylinder)
let offsetNode = SCNNode()
offsetNode.addChildNode(cylinderNode)
cylinderNode.simdPosition.y = cylinder.height / 2
offsetNode.position = /*...*/ // set world-space position of end of cylinder
offsetNode.eulerAngles.x = /*...*/ // rotate cylinder around its end
The picture shows a simple UIView after applying the following transform:
- (CATransform3D) transformForOpenedMenu
{
CATransform3D transform = CATransform3DIdentity;
transform.m34 = -1.0 /450;
transform = CATransform3DRotate(transform, D2R(40), 0, 1, 0);
transform = CATransform3DTranslate(transform, 210, 150, -500);
return transform;
}
I'm trying to make the distances highlighted with black to have equal length. Could you please help me understand the logic behind the values and calculations?
Cheers
UPD Sept 13
Looks like removing 3DTranslate keeps distances equal. I see I can use layer's frame property to reposition rotated view to the bottom left of the screen. Not yet sure, but this might actually work.
The .m34 value you are setting is best set on the sublayerTransform of the containing view rather than the view you are transforming.
I don't fully understand the maths behind affine transforms so I made this project which allows me to play around with the transform values to achieve the effect I want. You can plug in the values from your code above and see what it looks like, though note that there is already a perspective value applied using the sublayerTransform property mentioned above.
For your specific case, I think you want to adjust the anchor point of the layer to (0.0,0.5) and apply the rotation transform only. This assumes you want the menu to swing back like a door, with the hinges on the left edge.
The problem you're seeing is caused by your CATransform3DTranslate call. You're essentially setting the Y Axis off center, and hence seeing a different perspective view of the frame.
Think of it this way;
You're standing in the center of a long narrow field stretching off into the horizon. The edge of the field appears as if it is converges to a center point somewhere off in the distance. The angle of each edge to the converging point will appear equal if you are at the center of the field. If, on the other hand, you move either to the left or the right, the angles change and one will seem greater than the other (inversely opposite of course).
This is essentially what is happening with your view; As your converging points are to the right, changing the Y axis away from 0 will have the same effect as moving to the left or right in my example above. You're no longer looking at the parallel lines from the center.
so in your code above Setting the ty in CATransform3DTranslate to 0 Should fix your problem I.E.
transform = CATransform3DTranslate(transform, 210, 0, -500);
You may also need to alter the tz and tx Value to make it fit.
OK, so what eventually solved my question is this:
3D transform on Y axis to swing the view like a door transform = CATransform3DRotate(transform, D2R(40), 0, 1, 0);
set Z anchor point on a layer, to move it back targetView.layer.anchorPointZ = 850;
adjust layer position so that the view is located slightly to the bottom left of the parent view:
newPosition.x += 135 * positionDirection;
newPosition.y += 70 * positionDirection;
This sequence adjusts position without CATransform3DTranslate and keeps the 'swinged' effect not distorted.
Thanks everybody!
Suppose you have quaternion that describes the rotation of a 3D Model.
What I want to do is, given an Object (with rotationQuaternion, side vector...), I want to align it to a target point.
For a spaceship, I want the cockpit to point to a target.
Here is some code I have ... It's not doing what I want and I don't know why...
if (_target._ray.Position != _obj._ray.Position)
{
Vector3 vec = Vector3.Normalize(_target._ray.Position - _obj._ray.Position);
float angle = (float)Math.Acos(Vector3.Dot(vec, _obj._ray.Direction));
Vector3 cross = Vector3.Cross(vec, _obj._ray.Direction);
if (cross == Vector3.Zero)
cross = _obj._side;
_obj._rotationQuaternion *= Quaternion.CreateFromAxisAngle(cross,angle);
}
// Updates direction, up, side vectors and model Matrix
_obj.UpdateMatrix();
after some time the rotationQuaternion is filled with almost Zero at X,Y,Z and W
Any help?
Thanks ;-)
This is a shortcut I've used to get the quaternion for lock-on-target rotation:
Matrix rot = Matrix.CreateLookAt(_arrow.Position, _cube.Position, Vector3.Down);
_arrow.Rotation = Quaternion.CreateFromRotationMatrix(rot);
For this example, I'm rendering an arrow and a cube, where the cube is moving around in a circle, and with the above code the arrow is always pointing at the cube. (Though I imagine there are some edge cases when cube is exactly above or below).
Once you get this quaternion (from spaceship to target), you can use Quaternion.Lerp() to interpolate between current ship rotation and the aligned one. This will give your rotation a smooth transition (not just snap to target).
Btw, might be that your rotation gets reduced to zero because you're using *= when assigning to it.
Your code's a bit funky.
if (_target._ray.Position != _obj._ray.Position)
{
This may or may not be correct. Clearly, you've overridden the equals comparator. The correct thing be be doing here would be to ensure that the dot-product between the two (unit-length) rays is close to 1. If the rays have the same origin, then presumably have equal 'positions' means they're the same.
Vector3 vec = Vector3.Normalize(_target._ray.Position - _obj._ray.Position);
This seems particularly wrong. Unless the minus operator has been overridden in a strange way, subtracting this way doesn't make sense.
Here's pseudocode for what I recommend:
normalize3(targetRay);
normalize3(objectRay);
angleDif = acos(dotProduct(targetRay,objectRay));
if (angleDif!=0) {
orthoRay = crossProduct(objectRay,targetRay);
normalize3(orthoRay);
deltaQ = quaternionFromAxisAngle(orthoRay,angleDif);
rotationQuaternion = deltaQ*rotationQuaternion;
normalize4(rotationQuaternion);
}
Two things to note here:
Quaternions are not commutative. I've assumed that your quaternions are rotating column vectors; so I put deltaQ on the left. It's not clear what your *= operator is doing.
It's important to regularly normalize your quaternions after multiplication. Otherwise small errors accumulate and they drift away from unit length causing all manner of grief.
OMG! It worked!!!
Vector3 targetRay = Vector3.Normalize(_target._ray.Position - _obj._ray.Position);
Vector3 objectRay = Vector3.Normalize(_obj._ray.Direction);
float angle = (float)Math.Acos(Vector3.Dot(targetRay, objectRay));
if (angle!=0)
{
Vector3 ortho = Vector3.Normalize(Vector3.Cross(objectRay, targetRay));
_obj._rotationQuaternion = Quaternion.CreateFromAxisAngle(ortho, angle) * _obj._rotationQuaternion;
_obj._rotationQuaternion.Normalize();
}
_obj.UpdateMatrix();
Thank you very much JCooper!!!
And niko I like the idea of Lerp ;-)
How to make a 2d world with fixed size, which would repeat itself when reached any side of the map?
When you reach a side of a map you see the opposite side of the map which merged togeather with this one. The idea is that if you didn't have a minimap you would not even notice the transition of map repeating itself.
I have a few ideas how to make it:
1) Keeping total of 3x3 world like these all the time which are exactly the same and updated the same way, just the players exists in only one of them.
2) Another way would be to seperate the map into smaller peaces and add them to required place when asked.
Either way it can be complicated to complete it. I remember that more thatn 10 years ago i played some game like that with soldiers following each other in a repeating wold shooting other AI soldiers.
Mostly waned to hear your thoughts about the idea and how it could be achieved. I'm coding in XNA(C#).
Another alternative is to generate noise using libnoise libraries. The beauty of this is that you can generate noise over a theoretical infinite amount of space.
Take a look at the following:
http://libnoise.sourceforge.net/tutorials/tutorial3.html#tile
There is also an XNA port of the above at: http://bigblackblock.com/tools/libnoisexna
If you end up using the XNA port, you can do something like this:
Perlin perlin = new Perlin();
perlin.Frequency = 0.5f; //height
perlin.Lacunarity = 2f; //frequency increase between octaves
perlin.OctaveCount = 5; //Number of passes
perlin.Persistence = 0.45f; //
perlin.Quality = QualityMode.High;
perlin.Seed = 8;
//Create our 2d map
Noise2D _map = new Noise2D(CHUNKSIZE_WIDTH, CHUNKSIZE_HEIGHT, perlin);
//Get a section
_map.GeneratePlanar(left, right, top, down);
GeneratePlanar is the function to call to get the sections in each direction that will connect seamlessly with the rest of your world.
If the game is tile based I think what you should do is:
Keep only one array for the game area.
Determine the visible area using modulo arithmetics over the size of the game area mod w and h where these are the width and height of the table.
E.g. if the table is 80x100 (0,0) top left coordinates with a width of 80 and height of 100 and the rect of the viewport is at (70,90) with a width of 40 and height of 20 you index with [70-79][0-29] for the x coordinate and [90-99][0-9] for the y. This can be achieved by calculating the index with the following formula:
idx = (n+i)%80 (or%100) where n is the top coordinate(x or y) for the rect and i is in the range for the width/height of the viewport.
This assumes that one step of movement moves the camera with non fractional coordinates.
So this is your second alternative in a little bit more detailed way. If you only want to repeat the terrain, you should separate the contents of the tile. In this case the contents will most likely be generated on the fly since you don't store them.
Hope this helped.