Shamelessly stolen light code

shaders/lighting.glsl

@@ -1,16 +1,44 @@
 uniform sampler2D texture;
-uniform float ambient;
+uniform vec2 resolution;
+uniform vec2 mouse;
+uniform float time;
 uniform bool has_texture;
 
-void main()
-{
-    // lookup the pixel in the texture
-    vec4 pixel = texture2D(texture, gl_TexCoord[0].xy);
+// The RGB values are the ambient light color
+// and the alpha is the ambient intensity
+uniform vec4 ambientData;
+// The RGB values are the light color
+// and the alpha is the light intensity
+uniform vec4 lightData;
+// Maximum radius of the light
+uniform float lightSize;
 
-    // multiply it by the color
-    vec4 col = gl_Color;
-    if (has_texture) {
-        col = gl_Color * pixel;
-    }
-    gl_FragColor = vec4(col.x * ambient, col.y * ambient, col.z * ambient, col.w);
+void main() {
+  // Light's position
+  vec2 position = mouse/resolution.xx;
+
+  // Makes the light change its size slightly to make a fire effect
+  float maxDistance = lightSize + 0.015*sin(time);
+  // Gets the distance from the light's position and the fragment coord
+  float distance = distance(gl_FragCoord.xy/resolution.xx, position);
+  // Calculates the amount of light for the fragment
+  float value = 1.0 - smoothstep(-0.2, maxDistance, distance);
+
+  // Gets the original color from the texture
+  vec4 pixel = texture2D(texture, gl_TexCoord[0].xy);
+  if (!has_texture) {
+    pixel = gl_Color;
+  }
+
+  // Applies the ambient light to the original pixel color
+  vec3 ambient = pixel.rgb * ambientData.rgb * ambientData.a;
+
+  // Calculates the light color for the pixel
+  vec3 light = lightData.rgb * lightData.a * clamp(value, 0.0, 1.0);
+
+  // Applies the light to the pixel
+  vec3 intensity = ambient + light;
+  vec3 final = pixel.rgb * intensity;
+
+  gl_FragColor = vec4(final, 1.0);
 }