javascript - WebGL fragment shader opacity -

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alright, first off, i'm pretty new @ glsl shaders, , i'm trying wrap head around following shader

#ifdef gl_es     //precision mediump float;     precision highp float;     #endif      uniform vec2 utimes;      varying vec2 texcoord;     varying vec2 screencoord;      void main(void) {         vec3 col;         float c;         vec2 tmpv = texcoord * vec2(0.8, 1.0) - vec2(0.95, 1.0);         c = exp(-pow(length(tmpv) * 1.8, 2.0));         col = mix(vec3(0.02, 0.0, 0.03), vec3(0.96, 0.98, 1.0) * 1.5, c);         gl_fragcolor = vec4(col * 0.5, 0);     }

so far, know gives me radial gradient (perhaps). i'd know how make transparent. i'm thinking need vec4 that, right?

you need turn on blending.

see http://www.senchalabs.org/philogl/philogl/examples/lessons/8/ , http://learningwebgl.com/blog/?p=859‎.

without blending, depth , color buffers updated without taking care in buffer, overwrite data. blending on, , depending on type of blending function using, buffers updated data takes previsouly rendered data count.

this part interesting you:

gl.blendfunc(gl.src_alpha, gl.one); gl.enable(gl.blend); gl.disable(gl.depth_test);

hope helps.


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