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spotlight example, each spot has own radius, mouse countrol (#1148)

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NB glsl100 shader needs testing on "bare metal"

Co-authored-by: codifies <nospam@antispam.com>
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chriscamacho 2020-03-25 09:28:16 +00:00 • committed by GitHub
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commit 2dbcef218c
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3 changed files with 148 additions and 58 deletions
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63
examples/shaders/resources/shaders/glsl100/spotlight.fs
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@ -2,50 +2,67 @@
precision mediump float;
#define MAX_SPOTS 4
#define RADIUS 256.0
#define INNER 200.0
#define MAX_SPOTS 3
// Inputs
// array of spotlight positions
uniform vec2 spots[MAX_SPOTS];
uniform float screenWidth; // width of the screen
struct Spot {
vec2 pos; // window coords of spot
float inner; // inner fully transparent centre radius
float radius; // alpha fades out to this radius
};
uniform Spot spots[MAX_SPOTS]; // Spotlight positions array
uniform float screenWidth; // Width of the screen
void main()
{
float alpha;
float alpha = 1.0;
// get the position of the current fragment (screen coordinates!)
vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
// find out which spotlight is nearest
float d = 65000.0; // some high value
float di = 0.0;
int fi = -1;
for (int i = 0; i < MAX_SPOTS; i++)
{
di = distance(pos, spots[i]);
if (d > di) d = di;
for (int j = 0; j < MAX_SPOTS; j++)
{
float dj = distance(pos, spots[j].pos) - spots[j].radius + spots[i].radius;
if (d > dj )
{
d = dj;
fi = i;
}
}
}
// d now equals distance to nearest spot...
if (d > RADIUS) {
alpha = 1.0;
} else {
if (d < INNER) {
alpha = 0.0;
} else {
alpha = (d - INNER) / (RADIUS - INNER);
// allowing for the different radii of all spotlights
if (fi != -1) {
if (d > spots[fi].radius)
{
alpha = 1.0;
}
else
{
if (d < spots[fi].inner)
{
alpha = 0.0;
}
else
{
alpha = (d - spots[fi].inner) / (spots[fi].radius - spots[fi].inner);
}
}
}
// right hand side of screen is dimly lit, could make the
// threshold value user definable.
if (pos.x > screenWidth/2.0 && alpha > 0.9) {
alpha = 0.9;
}
// Right hand side of screen is dimly lit,
// could make the threshold value user definable
if ((pos.x > screenWidth/2.0) && (alpha > 0.9)) alpha = 0.9;
// could make the black out colour user definable...
gl_FragColor = vec4( 0, 0, 0, alpha);