mirror of
https://github.com/tanema/light_world.lua.git
synced 2024-12-24 20:24:19 +00:00
82 lines
3.5 KiB
GLSL
82 lines
3.5 KiB
GLSL
/*
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Copyright (c) 2014 Tim Anema
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light shadow, shine and normal shader all in one
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*/
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#define PI 3.1415926535897932384626433832795
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extern vec2 screenResolution; //size of the screen
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extern Image shadowMap; //a canvas containing shadow data only
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extern vec3 lightPosition; //the light position on the screen(not global)
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extern vec3 lightColor; //the rgb color of the light
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extern float lightRange; //the range of the light
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extern float lightSmooth; //smoothing of the lights attenuation
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extern vec2 lightGlow; //how brightly the light bulb part glows
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extern float lightAngle; //if set, the light becomes directional to a slice lightAngle degrees wide
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extern float lightDirection; //which direction to shine the light in if directional in degrees
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extern bool invert_normal; //if the light should invert normals
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//calculate if a pixel is within the light slice
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bool not_in_slice(vec2 pixel_coords){
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float angle = atan(lightPosition.x - pixel_coords.x, pixel_coords.y - lightPosition.y) + PI;
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bool pastRightSide = angle < mod(lightDirection + lightAngle, PI * 2);
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bool pastLeftSide = angle > mod(lightDirection - lightAngle, PI * 2);
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bool lightUp = lightDirection - lightAngle > 0 && lightDirection + lightAngle < PI * 2;
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return (lightUp && (pastRightSide && pastLeftSide)) || (!lightUp && (pastRightSide || pastLeftSide));
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}
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vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 pixel_coords) {
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vec4 pixelColor = Texel(texture, texture_coords);
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vec4 shadowColor = Texel(shadowMap, texture_coords);
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float dist = distance(lightPosition, vec3(pixel_coords, 1.0));
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//if the pixel is within this lights range
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if(dist > lightRange) {
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//not in range draw in shadows
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return vec4(0.0, 0.0, 0.0, 1.0);
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}else{
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//if the light is a slice and the pixel is not inside
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if(lightAngle > 0.0 && not_in_slice(pixel_coords)) {
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return vec4(0.0, 0.0, 0.0, 1.0);
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}
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vec3 normal;
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if(pixelColor.a > 0.0) {
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//if on the normal map ie there is normal map data
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//so get the normal data
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if(invert_normal) {
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normal = normalize(vec3(pixelColor.r, 1 - pixelColor.g, pixelColor.b) * 2.0 - 1.0);
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} else {
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normal = normalize(pixelColor.rgb * 2.0 - 1.0);
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}
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} else {
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// not on the normal map so it is the floor with a normal point strait up
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normal = vec3(0.0, 0.0, 1.0);
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}
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//calculater attenuation of light based on the distance
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float att = clamp((1.0 - dist / lightRange) / lightSmooth, 0.0, 1.0);
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// if not on the normal map draw attenuated shadows
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if(pixelColor.a == 0.0) {
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//start with a dark color and add in the light color and shadow color
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vec4 pixel = vec4(0.0, 0.0, 0.0, 1.0);
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if (lightGlow.x < 1.0 && lightGlow.y > 0.0) {
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pixel.rgb = clamp(lightColor * pow(att, lightSmooth) + pow(smoothstep(lightGlow.x, 1.0, att), lightSmooth) * lightGlow.y, 0.0, 1.0);
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} else {
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pixel.rgb = lightColor * pow(att, lightSmooth);
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}
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//If on the shadow map add the shadow color
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if(shadowColor.a > 0.0) {
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pixel.rgb = pixel.rgb * shadowColor.rgb;
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}
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return pixel;
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} else {
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//on the normal map, draw normal shadows
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vec3 dir = vec3((lightPosition.xy - pixel_coords.xy) / screenResolution.xy, lightPosition.z);
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dir.x *= screenResolution.x / screenResolution.y;
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vec3 diff = lightColor * max(dot(normalize(normal), normalize(dir)), 0.0);
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//return the light that is effected by the normal and attenuation
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return vec4(diff * att, 1.0);
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}
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}
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}
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