189 lines
6.0 KiB
GLSL
189 lines
6.0 KiB
GLSL
//this shader is a light shader. ideally drawn with a quad covering the entire region
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//the output is contribution from this light (which will be additively blended)
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//you can blame Electro for much of the maths in here.
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//fixme: no fog
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//s_t0 is the normals and depth
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//output should be amount of light hitting the surface.
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varying vec4 tf;
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#ifdef VERTEX_SHADER
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void main()
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{
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tf = ftetransform();
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gl_Position = tf;
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}
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#endif
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#ifdef FRAGMENT_SHADER
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uniform sampler2D s_t0; //norm.xyz, depth
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uniform vec3 l_lightposition;
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uniform mat4 m_invviewprojection;
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uniform vec3 l_lightcolour;
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uniform float l_lightradius;
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uniform mat4 l_cubematrix;
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#ifdef PCF
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#define USE_ARB_SHADOW
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#ifndef USE_ARB_SHADOW
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//fall back on regular samplers if we must
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#define sampler2DShadow sampler2D
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#endif
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uniform sampler2DShadow s_shadowmap;
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uniform vec4 l_shadowmapproj; //light projection matrix info
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uniform vec2 l_shadowmapscale; //xy are the texture scale, z is 1, w is the scale.
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vec3 ShadowmapCoord(vec4 cubeproj)
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{
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#ifdef SPOT
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//bias it. don't bother figuring out which side or anything, its not needed
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//l_projmatrix contains the light's projection matrix so no other magic needed
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return ((cubeproj.xyz-vec3(0.0,0.0,0.015))/cubeproj.w + vec3(1.0, 1.0, 1.0)) * vec3(0.5, 0.5, 0.5);
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//#elif defined(CUBESHADOW)
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// vec3 shadowcoord = vshadowcoord.xyz / vshadowcoord.w;
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// #define dosamp(x,y) shadowCube(s_shadowmap, shadowcoord + vec2(x,y)*texscale.xy).r
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#else
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//figure out which axis to use
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//texture is arranged thusly:
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//forward left up
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//back right down
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vec3 dir = abs(cubeproj.xyz);
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//assume z is the major axis (ie: forward from the light)
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vec3 t = cubeproj.xyz;
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float ma = dir.z;
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vec3 axis = vec3(0.5/3.0, 0.5/2.0, 0.5);
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if (dir.x > ma)
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{
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ma = dir.x;
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t = cubeproj.zyx;
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axis.x = 0.5;
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}
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if (dir.y > ma)
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{
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ma = dir.y;
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t = cubeproj.xzy;
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axis.x = 2.5/3.0;
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}
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//if the axis is negative, flip it.
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if (t.z > 0.0)
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{
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axis.y = 1.5/2.0;
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t.z = -t.z;
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}
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//we also need to pass the result through the light's projection matrix too
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//the 'matrix' we need only contains 5 actual values. and one of them is a -1. So we might as well just use a vec4.
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//note: the projection matrix also includes scalers to pinch the image inwards to avoid sampling over borders, as well as to cope with non-square source image
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//the resulting z is prescaled to result in a value between -0.5 and 0.5.
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//also make sure we're in the right quadrant type thing
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return axis + ((l_shadowmapproj.xyz*t.xyz + vec3(0.0, 0.0, l_shadowmapproj.w)) / -t.z);
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#endif
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}
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float ShadowmapFilter(vec4 vtexprojcoord)
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{
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vec3 shadowcoord = ShadowmapCoord(vtexprojcoord);
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#if 0//def GL_ARB_texture_gather
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vec2 ipart, fpart;
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#define dosamp(x,y) textureGatherOffset(s_shadowmap, ipart.xy, vec2(x,y)))
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vec4 tl = step(shadowcoord.z, dosamp(-1.0, -1.0));
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vec4 bl = step(shadowcoord.z, dosamp(-1.0, 1.0));
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vec4 tr = step(shadowcoord.z, dosamp(1.0, -1.0));
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vec4 br = step(shadowcoord.z, dosamp(1.0, 1.0));
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//we now have 4*4 results, woo
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//we can just average them for 1/16th precision, but that's still limited graduations
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//the middle four pixels are 'full strength', but we interpolate the sides to effectively give 3*3
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vec4 col = vec4(tl.ba, tr.ba) + vec4(bl.rg, br.rg) + //middle two rows are full strength
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mix(vec4(tl.rg, tr.rg), vec4(bl.ba, br.ba), fpart.y); //top+bottom rows
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return dot(mix(col.rgb, col.agb, fpart.x), vec3(1.0/9.0)); //blend r+a, gb are mixed because its pretty much free and gives a nicer dot instruction instead of lots of adds.
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#else
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#ifdef USE_ARB_SHADOW
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//with arb_shadow, we can benefit from hardware acclerated pcf, for smoother shadows
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#define dosamp(x,y) shadow2D(s_shadowmap, shadowcoord.xyz + (vec3(x,y,0.0)*l_shadowmapscale.xyx)).r
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#else
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//this will probably be a bit blocky.
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#define dosamp(x,y) float(texture2D(s_shadowmap, shadowcoord.xy + (vec2(x,y)*l_shadowmapscale.xy)).r >= shadowcoord.z)
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#endif
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float s = 0.0;
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#if r_glsl_pcf >= 1 && r_glsl_pcf < 5
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s += dosamp(0.0, 0.0);
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return s;
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#elif r_glsl_pcf >= 5 && r_glsl_pcf < 9
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s += dosamp(-1.0, 0.0);
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s += dosamp(0.0, -1.0);
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s += dosamp(0.0, 0.0);
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s += dosamp(0.0, 1.0);
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s += dosamp(1.0, 0.0);
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return s/5.0;
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#else
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s += dosamp(-1.0, -1.0);
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s += dosamp(-1.0, 0.0);
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s += dosamp(-1.0, 1.0);
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s += dosamp(0.0, -1.0);
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s += dosamp(0.0, 0.0);
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s += dosamp(0.0, 1.0);
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s += dosamp(1.0, -1.0);
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s += dosamp(1.0, 0.0);
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s += dosamp(1.0, 1.0);
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return s/9.0;
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#endif
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#endif
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}
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#else
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float ShadowmapFilter(vec4 vtexprojcoord)
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{
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return 1.0;
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}
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#endif
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vec3 calcLightWorldPos(vec2 screenPos, float depth)
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{
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vec4 pos = m_invviewprojection * vec4(screenPos.xy, (depth*2.0)-1.0, 1.0);
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return pos.xyz / pos.w;
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}
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void main ()
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{
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vec3 lightColour = l_lightcolour.rgb;
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float lightIntensity = 1.0;
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float lightAttenuation = l_lightradius; // fixme: just use the light radius for now, use better near/far att math separately once working
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float radiusFar = l_lightradius;
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float radiusNear = l_lightradius*0.5;
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vec2 fc;
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fc = tf.xy / tf.w;
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vec4 data = texture2D(s_t0, (1.0 + fc) / 2.0);
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float depth = data.a;
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vec3 norm = data.xyz;
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/* calc where the wall that generated this sample came from */
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vec3 worldPos = calcLightWorldPos(fc, depth);
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/*we need to know the cube projection (for both cubemaps+shadows)*/
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vec4 cubeaxis = l_cubematrix*vec4(worldPos.xyz, 1.0);
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/*calc diffuse lighting term*/
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vec3 lightDir = l_lightposition - worldPos;
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float zdiff = 1.0 - clamp(length(lightDir) / lightAttenuation, 0.0, 1.0);
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float atten = (radiusFar * zdiff) / (radiusFar - radiusNear);
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atten = pow(atten, 2.0);
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lightDir = normalize(lightDir);
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float nDotL = dot(norm, lightDir);
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float lightDiffuse = max(0.0, nDotL) * atten;
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//fixme: apply fog
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//fixme: output a specular term
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//fixme: cubemap filters
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gl_FragColor = vec4(lightDiffuse * (lightColour * lightIntensity) * ShadowmapFilter(cubeaxis), 1.0);
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}
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#endif
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