Examples » 3D Fluid Simulation » Shaders/ParticleSphereShader.frag source

/*
    This file is part of Magnum.

    Original authors — credit is appreciated but not required:

        2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 —
            Vladimír Vondruš <mosra@centrum.cz>
        2019 — Nghia Truong <nghiatruong.vn@gmail.com>

    This is free and unencumbered software released into the public domain.

    Anyone is free to copy, modify, publish, use, compile, sell, or distribute
    this software, either in source code form or as a compiled binary, for any
    purpose, commercial or non-commercial, and by any means.

    In jurisdictions that recognize copyright laws, the author or authors of
    this software dedicate any and all copyright interest in the software to
    the public domain. We make this dedication for the benefit of the public
    at large and to the detriment of our heirs and successors. We intend this
    dedication to be an overt act of relinquishment in perpetuity of all
    present and future rights to this software under copyright law.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

uniform highp mat4 projectionMatrix;
uniform highp vec3 lightDir;

uniform vec3 ambientColor;
uniform vec3 specularColor;
uniform float shininess;

uniform float particleRadius;

flat in vec3 viewCenter;
flat in vec3 color;
out lowp vec4 fragmentColor;

vec3 shadeLight(vec3 normal, vec3 fragPos, vec3 viewDir) {
    vec3 halfDir  = normalize(lightDir - viewDir);
    vec3 diffuse  = max(dot(normal, lightDir), 0.0)*color;
    vec3 specular = pow(max(dot(halfDir, normal), 0.0), shininess)*specularColor;

    return ambientColor + diffuse * 0.5 + specular; /* scale diffuse to 0.5 */
}

void main() {
    vec3 viewDir = normalize(viewCenter);
    vec3 normal;
    vec3 fragPos;

    normal.xy = gl_PointCoord.xy*vec2(2.0, -2.0) + vec2(-1.0, 1.0);
    float mag = dot(normal.xy, normal.xy);
    if(mag > 1.0) discard; /* outside the sphere */

    normal.z = sqrt(1.0 - mag);
    fragPos  = viewCenter + normal*particleRadius; /* correct fragment position */

    mat4 prjMatTransposed = transpose(projectionMatrix);
    float z = dot(vec4(fragPos, 1.0), prjMatTransposed[2]);
    float w = dot(vec4(fragPos, 1.0), prjMatTransposed[3]);
    gl_FragDepth = 0.5*(z/w + 1.0); /* correct fragment depth */

    fragmentColor = vec4(shadeLight(normal, fragPos, viewDir), 1.0);
}