opengl - Spot light effect does not work correctly using GLSL shaders -

i'm working on personal graphic engine , started develop spot lights. problem rendering not logical. sake of simplicity cleaned informations light , texture managing inside shaders example below.

here's vertex shader code :

#version 400  layout (location = 0) in vec3 vertexposition;  uniform mat4 modelviewmatrix; uniform mat4 mvp;  out vec3 vposition;  void main(void) {     vposition = vec3(modelviewmatrix * vec4(vertexposition, 1.0f));     //eye coordinates vertex position     gl_position = mvp * vec4(vertexposition, 1.0f); } 

and fragment shader code :

#version 400  in vec3 position;   //in eye coordinates  layout (location = 0) out vec4 fragcolor;  uniform int lightcount;  struct spotlight {     vec4 position;      //already in eye coordinates     vec3 la, ld, ls;     vec3 direction;     float exponent;     float cutoff; };  uniform spotlight lightinfos[1];  vec3 getlightintensity(void) {     vec3 lightintensity = vec3(0.0f);      (int idx = 0; idx < lightcount; idx++)     {         vec3 lightdirnorm = normalize(vec3(lightinfos[idx].position) - position);         vec3 spotdirnorm = normalize(lightinfos[idx].direction);         float angle = acos(dot(-lightdirnorm, spotdirnorm));         float cutoff = radians(clamp(lightinfos[idx].cutoff, 0.0f, 90.0f));          vec3 ambient = vec3(0.1f, 0.1f, 0.8f);      //color out of spotlight's cone.         vec3 spotcolor = vec3(0.1f, 0.8f, 0.1f);    //color within spotlight's cone.          if (angle < cutoff)         {             lightintensity = spotcolor;         }         else         {             lightintensity = ambient;         }     }     return (lightintensity); }  void main(void) {     fragcolor = vec4(getlightintensity(), 1.0f); } 

here's c++ code send light position properties :

glm::vec4 lightpositionvec = viewmatrix * glm::vec4(lightposition[0], lightposition[1], lightposition[2], lightposition[3]);  program->setuniform(std::string("lightinfos[").append(utils::tostring<int>(idx)).append("].position").c_str(), lightpositionvec); 

here's spot light properties :

<position x="0.0" y="2.0" z="0.0" w="1" /> <direction x="0.0" y="-1.0" z="0.0" /> <exponent>3.0</exponent> <cutoff>50.0</cutoff> 

the view properties :

<camera name="cam1">   <perspective fovy="70.0" ratio="1.0" nearclipplane="0.1" farclipplane="1000.0"/>   <lookat>      <eye x="0.0" y="50.0" z="50.0" />      <target x="0.0" y="0.0" z="0.0" />      <up x="0.0" y="1.0" z="0.0"/>   </lookat> </camera> 

i checked these informations before sending them program shader in c++ code , correct.

and here's result :

and if place camera closer plane following camera properties :

 <camera name="cam1">       <perspective fovy="70.0" ratio="1.0" nearclipplane="0.1" farclipplane="1000.0"/>       <lookat>          <eye x="0.0" y="10.0" z="20.0" />          <target x="0.0" y="0.0" z="0.0" />          <up x="0.0" y="1.0" z="0.0"/>       </lookat>     </camera> 

the result following (closer reality still not correct) :

as can see, it's not logical : have spot in x=0, y=1, z=0, downward spot light direction (x=0, y=-1, z=0) don't understand result. plus, vectors in eye coordinates. have impression spot light effect depends position of camera. can me ?

worked several types of lights: directional, spotlight, point light

here code

https://code.google.com/p/jpcsp/source/browse/trunk/src/jpcsp/graphics/shader.vert?r=1639

http://en.wikibooks.org/wiki/glsl_programming/glut/specular_highlights