Hello to everyone!
It’s been a long time that i code in OF, and i decide today, to try the shaders and their code…
…So i’m trying to re-use an old code, i find it on internet, to make a simple zoom effect.
I create a class with it and some image… but i think i missed something, because it is not really working…
i show you the code: can you tell me what i missed please? First time with it… and i need to know if i’m in the rigth way or not 
#include “bluetag.h”
bluetag::bluetag()
{
shader.load("shaders/zoom.vert","shaders/zoom.frag"); zoomRadius = 40.0; zoomMinVal = 0.1; zoomMaxVal = 1.0;
fbo.allocate(ofGetWidth(), ofGetHeight(), GL_RGBA);
map1.loadImage(“bluetag/map1.jpg”);
map2.loadImage(“bluetag/map2.jpg”);
map3.loadImage(“bluetag/map3.jpg”);
map4.loadImage(“bluetag/map4.jpg”);
}
void bluetag::draw(int handX, int handY)
{
fbo.begin();
map1.draw(0,0,ofGetWidth()/4,ofGetHeight()); map2.draw(ofGetWidth()/4,0,ofGetWidth()/4,ofGetHeight());
fbo.end();
shader.begin();
fbo.draw(0,0); pos.set(handX,handY ); shader.setUniform2i("circlePos", pos.x, fbo.getHeight() - pos.y); shader.setUniform1f( "circleRadius", zoomRadius ); shader.setUniform1f( "minZoom", zoomMinVal ); shader.setUniform1f( "maxZoom", zoomMaxVal );
shader.end();
}
and the zoom.frag :
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect src_tex_unit0;
uniform vec2 src_tex_offset0;
uniform vec2 circlePos;
uniform float circleRadius;
uniform float minZoom;
uniform float maxZoom;
vec4 color;
void main( void )
{
vec2 st = gl_TexCoord[0].st;
//check if our pixels fit in the bounding rect - so we avoid expensive operations like sqrt.
float maxX = circlePos.x + circleRadius; float minX = circlePos.x - circleRadius;
float maxY = circlePos.y + circleRadius; float minY = circlePos.y - circleRadius;
if( st.s > minX && st.s < maxX && st.t > minY && st.t < maxY){
float relX = st.s - circlePos.x; float relY = st.t - circlePos.y;
float ang = atan(relY, relX); float dist = sqrt(relX*relX + relY*relY);
if( dist <= circleRadius ){
//figure a zoom value for the pixel based on its distance from the center of the circle float newRad = dist * ( (maxZoom * dist/circleRadius) + minZoom );
float newX = circlePos.x + cos( ang ) * newRad; float newY = circlePos.y + sin( ang ) * newRad;
gl_FragColor = texture2DRect(src_tex_unit0, vec2(newX, newY) );
}else{ //just draw the pixels as normal gl_FragColor = texture2DRect(src_tex_unit0, st ); }
}else{ //just draw the pixels as normal gl_FragColor = texture2DRect(src_tex_unit0, st ); }}#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect src_tex_unit0;
uniform vec2 src_tex_offset0;
uniform vec2 circlePos;
uniform float circleRadius;
uniform float minZoom;
uniform float maxZoom;
vec4 color;
void main( void )
{
vec2 st = gl_TexCoord[0].st;
//check if our pixels fit in the bounding rect - so we avoid expensive operations like sqrt.
float maxX = circlePos.x + circleRadius; float minX = circlePos.x - circleRadius;
float maxY = circlePos.y + circleRadius; float minY = circlePos.y - circleRadius;
if( st.s > minX && st.s < maxX && st.t > minY && st.t < maxY){
float relX = st.s - circlePos.x; float relY = st.t - circlePos.y;
float ang = atan(relY, relX); float dist = sqrt(relX*relX + relY*relY);
if( dist <= circleRadius ){
//figure a zoom value for the pixel based on its distance from the center of the circle float newRad = dist * ( (maxZoom * dist/circleRadius) + minZoom );
float newX = circlePos.x + cos( ang ) * newRad; float newY = circlePos.y + sin( ang ) * newRad;
gl_FragColor = texture2DRect(src_tex_unit0, vec2(newX, newY) );
}else{ //just draw the pixels as normal gl_FragColor = texture2DRect(src_tex_unit0, st ); }
}else{ //just draw the pixels as normal gl_FragColor = texture2DRect(src_tex_unit0, st ); }}
and the .vert:
void main() {
gl_TexCoord[0] = gl_MultiTexCoord0;
gl_Position = ftransform();
}
