Hello,
I'm quite new here, and hope this topic hasn't been beaten to death (I looked a bit and it doesn't seem so, so here we go).
I'd like to make a simple script that take a picture with the camera (or picks one from the roll), apply a simple shader (GLSL), which basically turn the image B&W, and then save it to the iOS roll.
The example I found (filters.fsh in the games directory, and Simplexnoise) was meant to apply the effects in real time. The document scaning script seems to be closer to what I want, but instead of the enhance_contrast() function using CIFilter, I'd like to use a similar function with a custom shader.
How should I go about doing this? Here's my code so far:
Shader (bwShader.fsh) :
```precision highp float;
varying vec2 v_tex_coord;
uniform sampler2D u_texture;
uniform float u_scale;
uniform vec2 u_sprite_size;
uniform float u_time;
vec4 grayscale() {
vec4 color = texture2D(u_texture, v_tex_coord);
float contrast = 1.7;
color = (color - 0.5) * contrast + 0.5;
float gray = (color.r + color.g + color.b) / 3.0;
return vec4(gray, gray, gray, color.a);
}
void main() {
gl_FragColor = grayscale();
}
Python script, adapted from the scaning example :
import photos
import console
from objc_util import *
from scene import *
CIFilter, CIImage, CIContext, CIDetector, CIVector = map(ObjCClass, ['CIFilter', 'CIImage', 'CIContext', 'CIDetector', 'CIVector'])
def take_photo(filename='.temp.jpg'):
img = photos.capture_image()
if img:
img.save(filename)
return filename
def pick_photo(filename='.temp.jpg'):
img = photos.pick_image()
if img:
img.save(filename)
return filename
def load_ci_image(img_filename):
data = NSData.dataWithContentsOfFile_(img_filename)
if not data:
raise IOError('Could not read file')
ci_img = CIImage.imageWithData_(data)
return ci_img
def enhance_contrast(ci_img):
filter = CIFilter.filterWithName_('CIColorControls')
filter.setDefaults()
filter.setValue_forKey_(2.0, 'inputContrast')
filter.setValue_forKey_(0.0, 'inputSaturation')
filter.setValue_forKey_(ci_img, 'inputImage')
ci_img = filter.valueForKey_('outputImage')
filter = CIFilter.filterWithName_('CIHighlightShadowAdjust')
filter.setDefaults()
filter.setValue_forKey_(1.0, 'inputShadowAmount')
filter.setValue_forKey_(1.0, 'inputHighlightAmount')
filter.setValue_forKey_(ci_img, 'inputImage')
ci_img = filter.valueForKey_('outputImage')
return ci_img
def bw(ci_img,shader):
# PROBLEM HERE?
ci_img.shader = shader
return ci_img
def write_output(out_ci_img, filename='.output.jpg'):
ctx = CIContext.contextWithOptions_(None)
cg_img = ctx.createCGImage_fromRect_(out_ci_img, out_ci_img.extent())
ui_img = UIImage.imageWithCGImage_(cg_img)
c.CGImageRelease.argtypes = [c_void_p]
c.CGImageRelease.restype = None
c.CGImageRelease(cg_img)
c.UIImageJPEGRepresentation.argtypes = [c_void_p, CGFloat]
c.UIImageJPEGRepresentation.restype = c_void_p
data = ObjCInstance(c.UIImageJPEGRepresentation(ui_img.ptr, 0.75))
data.writeToFile_atomically_(filename, True)
return filename
def main():
with open('bwShader.fsh') as f:
src = f.read()
shader = Shader(src)
console.clear()
i = console.alert('Info', '...', 'Take Photo', 'Pick from Library')
if i == 1:
filename = take_photo()
else:
filename = pick_photo()
if not filename:
return
ci_img = load_ci_image(filename)
out_img = bw(ci_img,shader)
#out_img = enhance_contrast(ci_img)
out_file = write_output(out_img)
console.show_image(out_file)
print('Tap and hold the image to save it to your camera roll.')
if name == 'main':
main()
```
Thanks a lot. Once again, I hope I'm not too far off (or too imprecise) with this question.