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#version 120
// This shader is based on the basic lighting shader
// This only supports one light, which is directional, and it (of course) supports shadows
// Input vertex attributes (from vertex shader)
varying vec3 fragPosition;
varying vec2 fragTexCoord;
//varying in vec4 fragColor;
varying vec3 fragNormal;
// Input uniform values
uniform sampler2D texture0;
uniform vec4 colDiffuse;
// Input lighting values
uniform vec3 lightDir;
uniform vec4 lightColor;
uniform vec4 ambient;
uniform vec3 viewPos;
// Input shadowmapping values
uniform mat4 lightVP; // Light source view-projection matrix
uniform sampler2D shadowMap;
uniform int shadowMapResolution;
void main()
{
// Texel color fetching from texture sampler
vec4 texelColor = texture2D(texture0, fragTexCoord);
vec3 lightDot = vec3(0.0);
vec3 normal = normalize(fragNormal);
vec3 viewD = normalize(viewPos - fragPosition);
vec3 specular = vec3(0.0);
vec3 l = -lightDir;
float NdotL = max(dot(normal, l), 0.0);
lightDot += lightColor.rgb*NdotL;
float specCo = 0.0;
if (NdotL > 0.0) specCo = pow(max(0.0, dot(viewD, reflect(-(l), normal))), 16.0); // 16 refers to shine
specular += specCo;
vec4 finalColor = (texelColor*((colDiffuse + vec4(specular, 1.0))*vec4(lightDot, 1.0)));
// Shadow calculations
vec4 fragPosLightSpace = lightVP * vec4(fragPosition, 1);
fragPosLightSpace.xyz /= fragPosLightSpace.w; // Perform the perspective division
fragPosLightSpace.xyz = (fragPosLightSpace.xyz + 1.0f) / 2.0f; // Transform from [-1, 1] range to [0, 1] range
vec2 sampleCoords = fragPosLightSpace.xy;
float curDepth = fragPosLightSpace.z;
// Slope-scale depth bias: depth biasing reduces "shadow acne" artifacts, where dark stripes appear all over the scene.
// The solution is adding a small bias to the depth
// In this case, the bias is proportional to the slope of the surface, relative to the light
float bias = max(0.0008 * (1.0 - dot(normal, l)), 0.00008);
int shadowCounter = 0;
const int numSamples = 9;
// PCF (percentage-closer filtering) algorithm:
// Instead of testing if just one point is closer to the current point,
// we test the surrounding points as well.
// This blurs shadow edges, hiding aliasing artifacts.
vec2 texelSize = vec2(1.0f / float(shadowMapResolution));
for (int x = -1; x <= 1; x++)
{
for (int y = -1; y <= 1; y++)
{
float sampleDepth = texture2D(shadowMap, sampleCoords + texelSize * vec2(x, y)).r;
if (curDepth - bias > sampleDepth)
{
shadowCounter++;
}
}
}
finalColor = mix(finalColor, vec4(0, 0, 0, 1), float(shadowCounter) / float(numSamples));
// Add ambient lighting whether in shadow or not
finalColor += texelColor*(ambient/10.0)*colDiffuse;
// Gamma correction
finalColor = pow(finalColor, vec4(1.0/2.2));
gl_FragColor = finalColor;
}
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