overte-HifiExperiments/interface/resources/shaders/deferred_light_limited.vert
2014-09-19 12:18:00 -07:00

60 lines
2.8 KiB
GLSL

#version 120
//
// deferred_light_limited.vert
// vertex shader
//
// Created by Andrzej Kapolka on 9/19/14.
// Copyright 2014 High Fidelity, Inc.
//
// Distributed under the Apache License, Version 2.0.
// See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
// the radius (hard cutoff) of the light effect
uniform float radius;
void main(void) {
// find the right "right" direction
vec3 firstRightCandidate = cross(gl_LightSource[1].spotDirection, vec3(0.0, 1.0, 0.0));
vec3 secondRightCandidate = cross(gl_LightSource[1].spotDirection, vec3(1.0, 0.0, 0.0));
vec3 right = mix(firstRightCandidate, secondRightCandidate, step(length(firstRightCandidate), length(secondRightCandidate)));
right = normalize(right);
// and the "up"
vec3 up = cross(right, gl_LightSource[1].spotDirection);
// and the "back," which depends on whether this is a spot light
vec3 back = -gl_LightSource[1].spotDirection * step(gl_LightSource[1].spotCosCutoff, 0.0);
// find the eight corners of the bounds
vec4 c0 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (-up - right + back), 1.0);
vec4 c1 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (-up + right + back), 1.0);
vec4 c2 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (up - right + back), 1.0);
vec4 c3 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (up + right + back), 1.0);
vec4 c4 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (-up - right + gl_LightSource[1].spotDirection), 1.0);
vec4 c5 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (-up + right + gl_LightSource[1].spotDirection), 1.0);
vec4 c6 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (up - right + gl_LightSource[1].spotDirection), 1.0);
vec4 c7 = gl_ProjectionMatrix * vec4(gl_LightSource[1].position.xyz +
radius * (up + right + gl_LightSource[1].spotDirection), 1.0);
// find their projected extents
vec2 extents = max(
max(max(gl_Vertex.xy * (c0.xy / max(c0.w, 0.001)), gl_Vertex.xy * (c1.xy / max(c1.w, 0.001))),
max(gl_Vertex.xy * (c2.xy / max(c2.w, 0.001)), gl_Vertex.xy * (c3.xy / max(c3.w, 0.001)))),
max(max(gl_Vertex.xy * (c4.xy / max(c4.w, 0.001)), gl_Vertex.xy * (c5.xy / max(c5.w, 0.001))),
max(gl_Vertex.xy * (c6.xy / max(c6.w, 0.001)), gl_Vertex.xy * (c7.xy / max(c7.w, 0.001)))));
// make sure they don't extend beyond the screen
extents = min(extents, vec2(1.0, 1.0));
gl_Position = vec4(gl_Vertex.xy * extents, 0.0, 1.0);
gl_TexCoord[0] = vec4(dot(gl_Position, gl_ObjectPlaneS[3]), dot(gl_Position, gl_ObjectPlaneT[3]), 0.0, 1.0);
}