spotlight example, each spot has own radius, mouse countrol (#1148)
NB glsl100 shader needs testing on "bare metal" Co-authored-by: codifies <nospam@antispam.com>
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3 changed files with 148 additions and 58 deletions
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@ -2,50 +2,67 @@
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precision mediump float;
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#define MAX_SPOTS 4
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#define RADIUS 256.0
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#define INNER 200.0
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#define MAX_SPOTS 3
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// Inputs
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// array of spotlight positions
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uniform vec2 spots[MAX_SPOTS];
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uniform float screenWidth; // width of the screen
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struct Spot {
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vec2 pos; // window coords of spot
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float inner; // inner fully transparent centre radius
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float radius; // alpha fades out to this radius
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};
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uniform Spot spots[MAX_SPOTS]; // Spotlight positions array
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uniform float screenWidth; // Width of the screen
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void main()
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{
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float alpha;
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float alpha = 1.0;
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// get the position of the current fragment (screen coordinates!)
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vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
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// find out which spotlight is nearest
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float d = 65000.0; // some high value
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float di = 0.0;
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int fi = -1;
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for (int i = 0; i < MAX_SPOTS; i++)
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{
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di = distance(pos, spots[i]);
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if (d > di) d = di;
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for (int j = 0; j < MAX_SPOTS; j++)
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{
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float dj = distance(pos, spots[j].pos) - spots[j].radius + spots[i].radius;
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if (d > dj )
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{
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d = dj;
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fi = i;
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}
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}
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}
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// d now equals distance to nearest spot...
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if (d > RADIUS) {
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alpha = 1.0;
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} else {
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if (d < INNER) {
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alpha = 0.0;
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} else {
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alpha = (d - INNER) / (RADIUS - INNER);
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// allowing for the different radii of all spotlights
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if (fi != -1) {
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if (d > spots[fi].radius)
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{
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alpha = 1.0;
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}
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else
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{
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if (d < spots[fi].inner)
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{
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alpha = 0.0;
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}
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else
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{
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alpha = (d - spots[fi].inner) / (spots[fi].radius - spots[fi].inner);
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}
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}
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}
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// right hand side of screen is dimly lit, could make the
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// threshold value user definable.
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if (pos.x > screenWidth/2.0 && alpha > 0.9) {
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alpha = 0.9;
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}
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// Right hand side of screen is dimly lit,
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// could make the threshold value user definable
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if ((pos.x > screenWidth/2.0) && (alpha > 0.9)) alpha = 0.9;
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// could make the black out colour user definable...
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gl_FragColor = vec4( 0, 0, 0, alpha);
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@ -9,36 +9,61 @@ out vec4 finalColor;
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// NOTE: Add here your custom variables
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#define MAX_SPOTS 2
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#define RADIUS 128
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#define INNER 96
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#define MAX_SPOTS 3
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uniform vec2 spots[MAX_SPOTS]; // Spotlight positions array
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struct Spot {
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vec2 pos; // window coords of spot
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float inner; // inner fully transparent centre radius
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float radius; // alpha fades out to this radius
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};
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uniform Spot spots[MAX_SPOTS]; // Spotlight positions array
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uniform float screenWidth; // Width of the screen
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void main()
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{
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float alpha = 0.0;
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float alpha = 1.0;
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// Get the position of the current fragment (screen coordinates!)
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vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
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// Find out which spotlight is nearest
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float d = 65000; // some high value
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float di = 0;
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int fi = -1; // found index
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for (int i = 0; i < MAX_SPOTS; i++)
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{
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di = distance(pos, spots[i]);
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if (d > di) d = di;
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for (int j = 0; j < MAX_SPOTS; j++)
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{
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float dj = distance(pos, spots[j].pos) - spots[j].radius + spots[i].radius;
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if (d > dj )
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{
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d = dj;
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fi = i;
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}
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}
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}
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// d now equals distance to nearest spot...
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if (d > RADIUS) alpha = 1.0;
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else
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{
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if (d < INNER) alpha = 0.0;
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else alpha = (d - INNER)/(RADIUS - INNER);
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// allowing for the different radii of all spotlights
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if (fi != -1) {
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if (d > spots[fi].radius)
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{
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alpha = 1.0;
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}
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else
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{
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if (d < spots[fi].inner)
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{
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alpha = 0.0;
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}
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else
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{
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alpha = (d - spots[fi].inner) / (spots[fi].radius - spots[fi].inner);
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}
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}
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}
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// Right hand side of screen is dimly lit,
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