I am making a game with a fog of war layer covering the board. I want to have a cursor that shows up when the player mouses over a tile, and I'm implementing this with a glow effect around the tile, also implemented using a shader.
I'm running into a strange issue: the glow effect works fine for positive x values (when the camera is set at x = -250, y = 250) but I can't see it for negative x values unless the camera gets rotated to almost completely vertical (or I move the camera underneath the fog of war layer).
It's hard to explain, so I've made a CodePen demonstrating the problem: https://codepen.io/jakedluhy/pen/QqzajN?editors=0010
I'm pretty new to custom shaders, so any insight or help would be appreciated. Here's the shaders for the fog of war:
// Vertex
varying vec4 vColor;
void main() {
vec3 cRel = cameraPosition - position;
float dx = (20.0 * cRel.x) / cRel.y;
float dz = (20.0 * cRel.z) / cRel.y;
gl_Position = projectionMatrix *
modelViewMatrix *
vec4(
position.x + dx,
position.y,
position.z + dz,
1.0
);
vColor = vec4(0.0, 0.0, 0.0, 0.7);
}
// Fragment
varying vec4 vColor;
void main() {
gl_FragColor = vColor;
}
And the shaders for the "glow":
// Vertex
varying vec4 vColor;
attribute float alpha;
void main() {
vColor = vec4(color, alpha);
gl_Position = projectionMatrix *
modelViewMatrix *
vec4(position, 1.0);
}
// Fragment
varying vec4 vColor;
void main() {
gl_FragColor = vColor;
}
The math in the vertex shader for the fog of war is to keep the fog in a relative position to the game board.
Tagging THREE.js and glsl because I'm not sure whether this is a THREE.js exclusive problem or not...
Edit: version 0.87.1
Your example looks pretty weird. By setting depthWrite:false on your fog material the two boxes render.
version 0.87.1
Related
Im in a Three.js project and Im trying to convert a square with a square texture inside into a trapezoid.
I manage to create the shape but the texture inside, although it fits/cover the shape it do it with an undesired distorsión.
Im using a PlaneBufferGeometry with ShaderMaterial and im trying to obtain this distorsion in the shader part (although it would be ok if it is done in the threejs geometry part).
This is my vertex:
uniform sampler2D uTexture;
varying vec2 vUv;
void main(){
float scaleTOP = 0.5;
float scaleBOTTOM = 1.0;
float scaleLEFT = 1.0;
float scaleRIGHT = 1.0;
float scaleX = mix(scaleBOTTOM, scaleTOP, uv.y);
float posX = position.x*scaleX;
float scaleY = mix(scaleLEFT, scaleRIGHT, uv.x);
float posY = position.y*scaleY;
vec3 finalPosition = vec3(posX, posY);
gl_Position = projectionMatrix * modelViewMatrix * vec4( finalPosition, 1.0 );
// Varyings:
vUv = uv;
}
And this is my fragment:
uniform sampler2D uTexture;
varying vec2 vUv;
void main() {
vec4 tex = texture2D ( uTexture, vUv );
gl_FragColor = vec4(tex.r, tex.g, tex.b, 1.0);
}
Unfortunately I manage to distort the square into the trapezoid but the texture is not distorted in the way I want. See figure to see the intended result:
Figure:
My vertex and fragment were ok.
The problem was that the Threejs geometry I was using had only 2 polygons. I was using:
this.bg_geometry = new THREE.PlaneBufferGeometry(width, height, 1, 1)
Thats it... with only one division which only created two triangles which actually can be seen in the figure I posted.
I changed the geometry to:
this.bg_geometry = new THREE.PlaneBufferGeometry(width, height, 100, 100)
...and now the texture is distorted as desired.
Anyway many thanks to #prisoner849 as he put me in the track to pass 4 points as uniforms uPoints in this order: TL,TR,BL,BR to set the shape of the plane.
My vertex shader looks now like this:
uniform vec3 uPoints[4];
varying vec2 vUv;
void main(){
vec3 baselineBottom = (uPoints[3] - uPoints[2]) * uv.x + uPoints[2];
vec3 baselineTop = (uPoints[1] - uPoints[0]) * uv.x + uPoints[0];
vec3 finalPosition = (baselineTop - baselineBottom) * uv.y + baselineBottom;
gl_Position = projectionMatrix * modelViewMatrix * vec4( finalPosition, 1.0 );
vUv = uv;
}
With three.js, I am trying to create the scene where a plane becomes transparent as the camera moves away from it.
And I textured the plane object with the round map tile which is edited from the square image below.
When I load the round image through ShaderMaterial the texture appears square like the original image.
The weird thing is it is rendered as intended when the image is loaded onto regular mesh material.
Could you tell me why three.js behaves this way? Also, how might I render round tile using shader while keeping its functionality to fade based on distance?
the full code is available here: https://codesandbox.io/s/tile-with-shader-7kw5v?file=/src/index.js
Here is an option, that takes in count only x and z coords of the plane and the camera.
vertex.glsl:
varying vec4 vPosition;
varying vec2 vUv;
void main() {
vPosition = modelMatrix * vec4(position, 1.);
vUv = uv;
gl_Position = projectionMatrix * viewMatrix * vPosition;
}
frag.glsl:
uniform vec3 u_color;
uniform vec3 u_camera;
uniform vec3 u_plane;
uniform float u_rad;
uniform sampler2D u_texture;
varying vec4 vPosition;
varying vec2 vUv;
void main() {
vec4 textureCol = texture2D(u_texture, vUv);
float rad = distance(vPosition.xz, u_camera.xz); // xz-plane
textureCol.a = 1.0 - step(1., rad / u_rad);
gl_FragColor = textureCol;
}
and u_rad uniform is
u_rad: { value: 50 },
I am using a PointCloud for fast rendering of sprites after this blog post. Everything works fine with the perspective camera. However, if I switch to the orthographic camera via viewer.navigation.toOrthographic() the points' sizes are not calculated correctly. Does anyone know what the issue is or where I might find some clue?
My vertex shader
#if NUM_CUTPLANES > 0
varying highp vec3 vWorldPosition;
#endif
attribute float mVisible;
attribute float mSize;
varying float vMVisible;
uniform float scale;
void main() {
vMVisible = mVisible;
#if NUM_CUTPLANES > 0
vec4 _worldPosition = modelMatrix * vec4( position, 1.0 );
vWorldPosition = _worldPosition.xyz;
#endif
vec4 mvPosition = modelViewMatrix * vec4(position, 1.0);
gl_Position = projectionMatrix * mvPosition;
gl_PointSize = mSize * (scale / (-mvPosition.z) );
}
Zoomed out
Zoomed in
Zoomed in a little bit more
The problem is in the last few lines of the fragment shader:
vec4 mvPosition = modelViewMatrix * vec4(position, 1.0);
gl_Position = projectionMatrix * mvPosition;
gl_PointSize = mSize * (scale / (-mvPosition.z) );
When using an orthographic projection instead of a perspective projection, the mvPosition (position transformed into the "normalized device coordinates") may have very different values, and so dividing the point size by mvPosition.z may yield unexpected results.
You may need to clamp the final point size by some constants (or by uniforms you provide from your JavaScript code), e.g.:
gl_PointSize = clamp(mSize * scale / -mvPosition.z, 10.0, 100.0);
Is there a possibility to cast shadow from a plane for which the texture plays a video with a chromakey shader ? My trial seams to answer by NO but I guess my shader is not adapted. The object is a simple PlabeBufferGeometry and the shader is :
vertexShader is :
varying vec2 vUv;
void main() {vUv = uv;
vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 ); gl_Position = projectionMatrix * mvPosition;
}
fragmentShader is :
uniform sampler2D vidtexture;
uniform vec3 color;
varying vec2 vUv;
void main()
{ vec3 tColor = texture2D( vidtexture, vUv ).rgb;
float a = (length(tColor - color) - 0.5) * 7.0;
gl_FragColor = vec4(tColor, a);}
Have you tried using the discard keyword? If your frag shader encounters that keyword, it won't render that fragment, it's as if it didn't exist. You could use this to create shadow outlines defined by your chromakey instead of always geting a square shadow.
void main(){
vec3 tColor = texture2D( vidtexture, vUv ).rgb;
float a = (length(tColor - color) - 0.5) * 7.0;
// Do not render pixels that are less than 10% opaque
if (a < 0.1) discard;
gl_FragColor = vec4(tColor, a);
}
This is the same approach Three.js uses for Material.alphaTest in all their built-in materials. You can see the GLSL source code for that command here.
I'm creating a glow effect for car stop lights and found a shader that makes it possible to always face the camera:
uniform vec3 viewVector;
uniform float c;
uniform float p;
varying float intensity;
void main() {
vec3 vNormal = normalize( normalMatrix * normal );
vec3 vNormel = normalize( normalMatrix * -viewVector );
intensity = pow( c - dot(vNormal, vNormel), p );
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}
This solution is quite simple and almost works. It reacts to camera movement and it would be great. BUT this element is a child of a car. The car itself is moving around and when it rotates the material stops pointing directly at the camera.
I don't want to use SpritePlugin or LensFlarePlugin because they slow down my game by 20fps so I'll stick to this lightweight solution.
I found a solution for Direct 3d that you have to remove rotation data from tranformation matrix, but I don't know how to do this in THREE.js
I guess that instead of adding calculations with car transformation there must be a way to simplify this shader instead.
How to simplify this shader so the material always faces the camera?
From the link below: "To do spherical billboarding, just remove all rotations by setting the identity matrix". How to do it ShaderMaterial in THREE.js?
http://www.geeks3d.com/20140807/billboarding-vertex-shader-glsl/
The problem here I think is intercepting transformation matrix from ShaderMaterial before it's passed to the shader, but I'm not sure.
Probably irrelevant but here's also fragment shader:
uniform vec3 glowColor;
varying float intensity;
void main() {
vec3 glow = glowColor * intensity;
gl_FragColor = vec4( glow, 1.0 );
}
edit: for now I found a workaround which is eliminating parent's rotation influence by setting opposite quaternion. Not perfect and it's happening in CPU not GPU
this.quaternion._x = -this.parent.quaternion._x;
this.quaternion._y = -this.parent.quaternion._y;
this.quaternion._z = -this.parent.quaternion._z;
this.quaternion._w = -this.parent.quaternion._w;
Are you looking for an implementation of billboarding? (make a 2D sprite always face camera) If so, all you need to do is this:
"vec3 billboard(vec2 v, mat4 view){",
" vec3 up = vec3(view[0][1], view[1][1], view[2][1]);",
" vec3 right = vec3(view[0][0], view[1][0], view[2][0]);",
" vec3 p = right * v.x + up * v.y;",
" return p;",
"}"
v is the offset from the center, basically the 4 vertices in a plane that faces the z-axis. Eg. (1.0, 1.0), (1.0, -1.0), (-1.0, 1.0), and (-1.0, -1.0).
Use it like so:
"vec3 worldPos = billboard(a_offset, u_view);"
// then do whatever else.