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Is it possible to have the objects I draw not have the image I set as the background?

I have this program where my canvas assumes a WebGL context and I'm trying to upload an image as the background, but when I do so, everything becomes the image itself:
I achieved this by fiddling with my css files and setting the background-image: to what I wanted. But I would really like if only the background itself would be the image, and not the objects I draw.
Any tips?
This is my shader.frag code:
precision highp float;
const int MAX_LIGHTS = 8;
struct LightInfo {
bool active;
bool directional;
vec3 pos;
vec3 ia;
vec3 id;
vec3 is;
};
struct MaterialInfo {
vec3 ka;
vec3 kd;
vec3 ks;
float shininess;
};
varying vec3 fNormal;
varying vec3 posC;
uniform int uNLights; // Effective number of lights used
uniform LightInfo uLight[MAX_LIGHTS]; // The array of lights present in the scene
uniform MaterialInfo uMaterial; // The material of the object being drawn
uniform mat4 mView;
uniform mat4 mViewNormals;
void main() {
for(int i = 0; i < MAX_LIGHTS; i++) {
if(i == uNLights) break;
if(uLight[i].active) {
vec3 L;
if(uLight[i].directional) {
L = normalize((mViewNormals * vec4(uLight[i].pos, 0.0)).xyz);
} else {
L = normalize((mView * vec4(uLight[i].pos, 1.0)).xyz - posC);
}
vec3 V = normalize(-posC);
vec3 N = normalize(fNormal);
vec3 R = reflect(-L, N);
float diffuseFactor = max(dot(N, L), 0.0);
float specularFactor = pow(max(dot(R, V), 0.0), uMaterial.shininess);
vec3 ambientColor = uLight[i].ia * uMaterial.ka;
vec3 diffuseColor = uLight[i].id * uMaterial.kd;
vec3 diffuse = diffuseFactor * diffuseColor;
vec3 specularColor = uLight[i].is * uMaterial.ks;
vec3 specular = specularFactor * specularColor;
if(dot(L, N) < 0.0) {
specular = vec3(0.0, 0.0, 0.0);
}
gl_FragColor.xyz += vec3(ambientColor + diffuse + specular);
}
}
}

Blur HTML5 canvas issue

The canvas does not allow me to use other domain URLs and show a cross-domain error.
I have to use this demo https://tympanus.net/Development/FlowmapDeformation/index3.html but I face some issues on the frontend.
At the front end of the demo, it shows blurs SVG image in the canvas.
Demo use below Vertex and fragment:
const vertex = `
attribute vec2 uv;
attribute vec2 position;
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = vec4(position, 0, 1);
}
`;
const fragment = `
precision highp float;
precision highp int;
uniform sampler2D tWater;
uniform sampler2D tFlow;
uniform float uTime;
varying vec2 vUv;
uniform vec4 res;
void main() {
// R and G values are velocity in the x and y direction
// B value is the velocity length
vec3 flow = texture2D(tFlow, vUv).rgb;
vec2 uv = .5 * gl_FragCoord.xy / res.xy ;
vec2 myUV = (uv - vec2(0.5))*res.zw + vec2(0.5);
myUV -= flow.xy * (0.15 * 0.5);
vec3 tex = texture2D(tWater, myUV).rgb;
gl_FragColor.rgb = vec3(tex.r, tex.g, tex.b);
gl_FragColor.a = tex.r;
}
`;
SVG image code:
let imgSize = [1600, 1200];
const img = new Image();
img.onload = () => (texture.image = img);
img.crossOrigin = "Anonymous";
img.src = "img/Alienation.svg";
const program = new Program(gl, {
vertex,
fragment,
uniforms: {
uTime: { value: 0 },
tWater: { value: texture },
res: {
value: new ogl.Vec4(window.innerWidth, window.innerHeight)
},
img: { value: new ogl.Vec2(imgSize[0], imgSize[1]) },
tFlow: flowmap.uniform
}
});
See the original SVG image - https://tympanus.net/Development/FlowmapDeformation/img/Alienation.svg
Check the attached screenshot for more information.

Shader linking fails without error message only on mobile devices

I'm working on a graphics engine written in C++. We currently can either build for desktop or for web (using emscripten). Both platforms utilize OpenGL ES 2.0.
I have a vertex and a fragment shader:
Vertex Shader
#version 100
attribute vec4 a_position;
attribute vec2 a_texcoord;
attribute vec3 a_normal;
attribute vec3 a_tangent;
attribute vec3 a_bitangent;
uniform mat4 u_model;
uniform mat4 u_view;
uniform mat4 u_projection;
uniform mat3 u_normalMatrix;
varying vec2 v_texcoord;
varying vec3 v_normal;
varying vec3 v_fragPos;
varying mat3 v_TBN;
void main()
{
vec3 T = normalize(vec3(u_model * vec4(a_tangent, 0.0)));
vec3 B = normalize(vec3(u_model * vec4(a_bitangent, 0.0)));
vec3 N = normalize(vec3(u_model * vec4(a_normal, 0.0)));
v_TBN = mat3(T, B, N);
gl_Position = u_projection * u_view * u_model * a_position;
v_texcoord = a_texcoord;
v_normal = u_normalMatrix * a_normal;
v_fragPos = vec3(u_model * a_position);
};
Fragment Shader
#version 100
precision mediump float;
varying vec2 v_texcoord;
varying vec3 v_normal;
varying vec3 v_fragPos;
varying mat3 v_TBN;
struct Material {
sampler2D diffuse;
sampler2D specular;
sampler2D normal;
float shininess;
};
struct Light {
int type;
vec3 position;
vec3 direction;
vec3 ambient;
vec3 diffuse;
vec3 specular;
float constant;
float linear;
float quadratic;
float cutOff;
float outerCutOff;
};
const int MAX_LIGHTS = 16;
uniform vec3 u_viewPos;
uniform Material u_material;
uniform Light u_lights[MAX_LIGHTS];
uniform int u_lightCount;
uniform bool normalMapping;
vec3 calcDirLight(Light light, vec3 normal, vec3 viewDir);
vec3 calcPointLight(Light light, vec3 normal, vec3 viewDir);
vec3 calcSpotLight(Light light, vec3 normal, vec3 viewDir);
void main()
{
vec3 lightOutput = vec3(0.0);
vec3 norm = normalize(v_normal);
if (normalMapping)
{
norm = texture2D(u_material.normal, v_texcoord).rgb;
norm = normalize(norm * 2.0 - 1.0);
norm = normalize(v_TBN * norm);
}
vec3 viewDir = normalize(u_viewPos - v_fragPos);
for(int i = 0; i < MAX_LIGHTS; i++)
{
if (i >= u_lightCount){break;}
if (u_lights[i].type == 0)
{
lightOutput += calcDirLight(u_lights[i], norm, viewDir)
}
else if (u_lights[i].type == 1)
{
lightOutput += calcPointLight(u_lights[i], norm, viewDir);
}
else if (u_lights[i].type == 2)
{
lightOutput += calcSpotLight(u_lights[i], norm, viewDir);
}
}
gl_FragColor = vec4(lightOutput, 1.0);
}
vec3 calcDirLight(Light light, vec3 normal, vec3 viewDir)
{
vec3 lightDir = normalize(-light.direction);
float diff = max(dot(normal, lightDir), 0.0);
vec3 reflectDir = reflect(-lightDir, normal);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), u_material.shininess);
vec3 ambient = light.ambient * vec3(texture2D(u_material.diffuse, v_texcoord));
vec3 diffuse = light.diffuse * diff * vec3(texture2D(u_material.diffuse, v_texcoord));
vec3 specular = light.specular * spec * vec3(texture2D(u_material.specular, v_texcoord));
return (ambient + diffuse + specular);
}
vec3 calcPointLight(Light light, vec3 normal, vec3 viewDir)
{
vec3 lightDir = normalize(light.position - v_fragPos);
float diff = max(dot(normal, lightDir), 0.0);
vec3 reflectDir = reflect(-lightDir, normal);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), u_material.shininess);
float distance = length(light.position - v_fragPos);
float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));
vec3 ambient = light.ambient * vec3(texture2D(u_material.diffuse, v_texcoord));
vec3 diffuse = light.diffuse * diff * vec3(texture2D(u_material.diffuse, v_texcoord));
vec3 specular = light.specular * spec * vec3(texture2D(u_material.specular, v_texcoord));
ambient *= attenuation;
diffuse *= attenuation;
specular *= attenuation;
return (ambient + diffuse + specular);
}
vec3 calcSpotLight(Light light, vec3 normal, vec3 viewDir)
{
vec3 lightDir = normalize(light.position - v_fragPos);
float diff = max(dot(normal, lightDir), 0.0);
vec3 reflectDir = reflect(-lightDir, normal);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), u_material.shininess);
float distance = length(light.position - v_fragPos);
float attenuation = 1.0 / (light.constant + light.linear * distance + light.quadratic * (distance * distance));
float theta = dot(lightDir, normalize(light.direction));
float epsilon = light.cutOff - light.outerCutOff;
float intensity = clamp((theta - light.outerCutOff) / epsilon, 0.0, 1.0);
vec3 ambient = light.ambient * vec3(texture2D(u_material.diffuse, v_texcoord));
vec3 diffuse = light.diffuse * diff * vec3(texture2D(u_material.diffuse, v_texcoord));
vec3 specular = light.specular * spec * vec3(texture2D(u_material.specular, v_texcoord));
ambient *= attenuation * intensity;
diffuse *= attenuation * intensity;
specular *= attenuation * intensity;
return (ambient + diffuse + specular);
};
They both compile without errors, but the linking stage fails. The info log (accessed using glGetProgramInfoLog) is empty.
The biggest problem is that it compiles and links perfectly fine on desktop native and desktop browsers (emscripten). It only fails linking on mobile devices.
I've spent hours trying to figure this out, without success. Is there anything obvious i might have missed?
Edit 1: This is the code that builds the shader program:
GLuint GLES2Shader::buildProgram(GLuint vertexShader, GLuint fragmentShader)
{
GL( GLuint programObject = glCreateProgram() );
GL( glAttachShader(programObject, vertexShader) );
GL( glAttachShader(programObject, fragmentShader) );
GL( glLinkProgram(programObject) );
//check if the program linked successfully
GLint linked;
GL( glGetProgramiv(programObject, GL_LINK_STATUS, &linked) );
if (!linked)
{
DEBUG( GLchar infoLog[512] );
DEBUG( glGetProgramInfoLog(programObject, 512, NULL, infoLog) );
DEBUG( LOGE("ERROR::SHADER::LINKING_FAILED %s", infoLog) );
GL( glDeleteProgram(programObject) );
return 0;
}
return programObject;
}

How to pass and use a lookup table in a shader with three.js

I have written a simple three.js of using a height map. This is the relevant code that creates the shader material:
function loadHeightMap() {
// fake a lookup table
var lut = [];
for ( var n=0; n<256; n++ ) {
lut.push(new THREE.Vector3(0.5, 0.4, 0.3));
}
var loader = new THREE.TextureLoader();
var zScale = 10;
var mapLoc = "https://s22.postimg.org/8n93ehmep/Terrain128.png";
loader.load(mapLoc, function ( texture ) {
// use "this." to create global object
this.customUniforms = {
zTexture: { type: "t", value: texture },
zScale: { type: "f", value: zScale },
zLut: { type: "v3v", value: lut }
};
var customMaterial = new THREE.ShaderMaterial({
uniforms: customUniforms,
vertexShader: document.getElementById( 'vertexShader' ).textContent,
fragmentShader: document.getElementById( 'fragmentShader' ).textContent,
side: THREE.DoubleSide
});
var planeGeo = new THREE.PlaneGeometry( 20, 20, 129, 129 );
var plane = new THREE.Mesh( planeGeo, customMaterial );
plane.rotation.x = -Math.PI / 2;
plane.position.y = 0;
scene.add(plane);
});
}
And here are the shaders:
<script id="vertexShader" type="x-shader/x-vertex">
uniform sampler2D zTexture;
uniform float zScale;
uniform vec3 zLut[ 256 ];
varying float vAmount;
void main() {
vec4 heightData = texture2D( zTexture, uv );
vAmount = heightData.r;
// move the position along the normal
vec3 newPosition = position + normal * zScale * vAmount;
gl_Position = projectionMatrix * modelViewMatrix * vec4( newPosition, 1.0 );
}
</script>
<script id="fragmentShader" type="x-shader/x-vertex">
uniform vec3 zLut[ 256 ];
varying float vAmount;
void main() {
int index = int(vAmount) * 255;
vec3 vColor = vec3(vAmount, vAmount, vAmount);
//gl_FragColor = vec4(zLut[index], 1.0);
gl_FragColor = vec4(vColor, 1.0);
}
The shaders and the height map part works fine. But I want to pass the lookup table (zLut). The above code works fine if I don't try to use the lookup table. A working example is here. I created a fiddle as well here but it fails because of CORS issues.
Any suggestions are welcome.

OK, solved this (mostly). The trick was to fetch the lookup color in the vertex shader, where one CAN index into an array with a non-const value. The pass the resulting color to the fragmentShader as a varying. So the two shaders end up being:
<script id="vertexShader" type="x-shader/x-vertex">
uniform sampler2D vTexture;
uniform float vScale;
uniform vec3 vLut[ 256 ];
varying vec3 vColor;
void main() {
vec4 heightData = texture2D( vTexture, uv );
// assuming map is grayscale it doesn't matter if you use r, g, or b.
float vAmount = heightData.r;
// fetch the color from the lookup table so it gets passed to the fragshader
int index = int(heightData.r * 255.0);
vColor = vLut[index];
// move the position along the normal
vec3 newPosition = position + normal * vScale * vAmount;
gl_Position = projectionMatrix * modelViewMatrix * vec4( newPosition, 1.0 );
}
</script>
<script id="fragmentShader" type="x-shader/x-vertex">
varying vec3 vColor;
void main() {
gl_FragColor = vec4(vColor, 1.0);
}
</script>
The remaining problem I have is that when rendered the colors are all flat. I tried forcing an update on the vertices in the animate function but didn't work. Still researching but the question here is solved (AFAIK).
You can see the result here

THREE.js Color texture by shader

i've added simple box to my scene, and I want to create shader that will add a texture to it and add color to this texture.
This is my vertex shader(nothing special about it):
<script id="vertexShader" type="x-shader/x-vertex">
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = projectionMatrix * modelViewMatrix * vec4(position,1.0);
}
</script>
And this is my fragment shader:
<script id="fragmentShader" type="x-shader/x-fragment">
uniform vec2 resolution;
uniform float time;
uniform sampler2D texture;
varying vec2 vUv;
uniform vec3 color;
varying vec3 vColor;
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
vec2 uv = fragCoord.xy / vec2(1920.0, 1920.0);
fragColor = vec4(uv, 0.5 + 0.5 * cos(time) * sin(time) ,1.0);
}
void main( void ) {
vec4 color = vec4(0.0,0.0,0.0,1.0);
mainImage( color, gl_FragCoord.xy );
color.w = 1.0;
gl_FragColor = texture2D(texture, vUv);
gl_FragColor = color;
}
</script>
As You can see, in two last lines i've sets gl_FragColor with texture and color.
When last line is gl_FragColor = color; The result is:
When i change order and last line is gl_FragColor = texture2D(texture, vUv); The result is:
This is the code that use shader and add a box to a scene:
var geometry = new THREE.BoxGeometry(.5, 1, .5);
uniforms = {
time: { type: "f", value: 1.0 },
resolution: { type: "v2", value: new THREE.Vector2() },
texture: { type: "t", value: THREE.ImageUtils.loadTexture("../img/disc.png") }
};
var material = new THREE.ShaderMaterial({
transparent: true,
uniforms: uniforms,
vertexShader: document.getElementById('vertexShader').textContent,
fragmentShader: document.getElementById('fragmentShader').textContent
});
var mesh = new THREE.Mesh(geometry, material);
scene.add(mesh);
Is there a possibility to color my texture(mix color and texture in object) by this shader in the same way like in the picture?

Just like any other variable setting it twice just makes it the 2nd result;
var foo;
foo = 123;
foo = 456;
foo now equals 456
If you want to combine the results you need to something yourself to combine them
gl_FragColor = texture2D(texture, vUv);
gl_FragColor = color;
Just means gl_FragColor equals color;
I'm guessing you want something like
gl_FragColor = texture2D(texture, vUv) * color;
But of course what math you use is up to you depending on what you're trying to achieve.
Given your example texture and color above multiplying the texture by the color you'll get a circle with a gradient color. It's not clear if that's the result you wanted.