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Tilt shift shader, modified from something @grapefrukt gave me
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| // Modified version of a tilt shift shader from Martin Jonasson (http://grapefrukt.com/) | |
| // Read http://notes.underscorediscovery.com/ for context on shaders and this file | |
| // License : MIT | |
| uniform sampler2D tex0; | |
| varying vec2 tcoord; | |
| varying vec4 color; | |
| //I am hardcoding the constants like a jerk, | |
| // Take note that blurring in a single pass (the two for loops below) is more expensive than separating | |
| // the x and the y blur into different passes. This was used where bleeding edge performance | |
| // was not crucial and is to illustrate a point. | |
| // Some interesting discussion : | |
| // http://theinstructionlimit.com/gaussian-blur-revisited-part-two | |
| const float bluramount = 1.0; | |
| const float center = 1.1; | |
| const float stepSize = 0.004; | |
| const float steps = 3.0; | |
| const float minOffs = (float(steps-1.0)) / -2.0; | |
| const float maxOffs = (float(steps-1.0)) / +2.0; | |
| void main() { | |
| float amount; | |
| vec4 blurred; | |
| //Work out how much to blur based on the mid point | |
| amount = pow((tcoord.y * center) * 2.0 - 1.0, 2.0) * bluramount; | |
| //This is the accumulation of color from the surrounding pixels in the texture | |
| blurred = vec4(0.0, 0.0, 0.0, 1.0); | |
| //From minimum offset to maximum offset | |
| for (float offsX = minOffs; offsX <= maxOffs; ++offsX) { | |
| for (float offsY = minOffs; offsY <= maxOffs; ++offsY) { | |
| //copy the coord so we can mess with it | |
| vec2 temp_tcoord = tcoord.xy; | |
| //work out which uv we want to sample now | |
| temp_tcoord.x += offsX * amount * stepSize; | |
| temp_tcoord.y += offsY * amount * stepSize; | |
| //accumulate the sample | |
| blurred += texture2D(tex0, temp_tcoord); | |
| } //for y | |
| } //for x | |
| //because we are doing an average, we divide by the amount (x AND y, hence steps * steps) | |
| blurred /= float(steps * steps); | |
| //return the final blurred color | |
| gl_FragColor = blurred; | |
| } //main | |
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