objective c - Shader doesn't work - OpenGL ES -

i have created program allows me display 3d objects , want make cut in relation object. here result : screen.

the screen shows can see through cut portion. decided use shader fill cut part.

i tried load shader , use in gluniform3f doesn't work. did several searches on internet, without results.

here class load shader:

- (id)initwithvertexshaderfilename:(nsstring *)vshaderfilename         fragmentshaderfilename:(nsstring *)fshaderfilename { nslog(fshaderfilename); if (self = [super init]) {     attributes = [[nsmutablearray alloc] init];     nsstring *vertshaderpathname, *fragshaderpathname;     program = glcreateprogram();      vertshaderpathname =[[nsbundle mainbundle]                          pathforresource:vshaderfilename                          oftype:@"vsh"                          indirectory:@"shader"];      if (![self compileshader:&vertshader                         type:gl_vertex_shader                         file:vertshaderpathname])         nslog(@"failed compile vertex shader");     else         nslog(@"vertex shader ok");      fragshaderpathname = [[nsbundle mainbundle]                           pathforresource:fshaderfilename                           oftype:@"fsh"                           indirectory:@"shader"];      if (![self compileshader:&fragshader                         type:gl_fragment_shader                         file:fragshaderpathname])         nslog(@"failed compile fragment shader");     else         nslog(@"fragment shader ok");     glattachshader(program, vertshader);     glattachshader(program, fragshader); }  return self; }  - (bool)compileshader:(gluint *)shader              type:(glenum)type              file:(nsstring *)file {     nslog(@"bonjour");     glint status;     const glchar *source;      source =     (glchar *)[[nsstring stringwithcontentsoffile:file                                      encoding:nsutf8stringencoding                                         error:nil] utf8string];    if (!source)    {        nslog(@"failed load vertex shader");        return no;    }     *shader = glcreateshader(type);    glshadersource(*shader, 1, &source, null);    glcompileshader(*shader);     glgetshaderiv(*shader, gl_compile_status, &status);    nsstring *intstring = [nsstring stringwithformat:@"%d", status];    return status = gl_true; }  #pragma mark - - (void)addattribute:(nsstring *)attributename {    if (![attributes containsobject:attributename])    {        [attributes addobject:attributename];        glbindattriblocation(program,                          [attributes indexofobject:attributename],                          [attributename utf8string]);    } }  - (gluint)attributeindex:(nsstring *)attributename {    return [attributes indexofobject:attributename]; }  - (gluint)uniformindex:(nsstring *)uniformname {    return glgetuniformlocation(program, [uniformname utf8string]); }  #pragma mark - - (bool)link {    glint status;     gllinkprogram(program);    glvalidateprogram(program);     glgetprogramiv(program, gl_link_status, &status);    if (status == gl_false)        return no;     if (vertshader)        gldeleteshader(vertshader);    if (fragshader)        gldeleteshader(fragshader);     return yes; }  - (void)use {     gluseprogram(program); } 

here function initialize shaders in main class:

- (void)setup {    glshader *theprogram = [[glshader alloc] initwithvertexshaderfilename:@"shader"                                                fragmentshaderfilename:@"shader"];    self.program = theprogram;     [self.program addattribute:@"position"];    [self.program addattribute:@"texturecoordinates"];     if (![self.program link])    {        nslog(@"link failed");         nsstring *proglog = [self.program programlog];        nslog(@"program log: %@", proglog);         nsstring *fraglog = [self.program fragmentshaderlog];        nslog(@"frag log: %@", fraglog);         nsstring *vertlog = [self.program vertexshaderlog];        nslog(@"vert log: %@", vertlog);         //[(glview *)self.view stopanimation];        self.program = nil;    }     texturecoordinateattribute = [program attributeindex:@"texturecoordinates"];    coloruniform = [program uniformindex:@"ucolor"];    textureuniform = [program uniformindex:@"texture"];    //coloruniform = glgetuniformlocation(self.program, "ucolor");     glenable(gl_depth_test);    glenable(gl_cull_face);    glenable(gl_texture_2d);    glenable(gl_blend);    glblendfunc(gl_one, gl_zero);     } 

here function want use shader:

 -(void) draw  {      [self.program use];      glclear(gl_color_buffer_bit | gl_depth_buffer_bit | gl_stencil_buffer_bit);      gldepthmask(true);      luniform3f(coloruniform,1.0, 1.0, 0.5);      [self drawsubtraction:image1 with:image2];   } 

here fragment shader:

precision highp float;  uniform vec3 ucolor; uniform vec3 ulight;  varying vec3 vnormal;  const float alpha = 0.7; void main(void) { float val = dot( vnormal, ulight ) * 0.4 + 0.6;  gl_fragcolor = vec4( ucolor * val, alpha); } 

am doing wrong ? has idea me ?

thanks.

your shader code looks ok. make sure passing in "texturecoordinates" attribute correctly vertex shader. need call glenablevertexattribarray() , glvertexattribpointer() @ point of initialization. depending on how rendering models might need ensure passing in vertices correctly well.

also i'm assuming [self drawsubtraction:image1 with:image2] calls gldrawarrays() or gldrawelements() @ point.

the xcode default opengl game project great place start loading shaders if want project compare against.