Sign in to follow this  

OpenGL Using std::vector to load data to VBO

This topic is 1858 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I have tried looking for the solution but I haven't found anything discussing the whole process.

I'm trying to write my own fractal generator. What I do is I generate coordinates with a color associated with it which is loaded into vector<Point> _points. _points is then used to load the vector<float> _vertexBuffer and vector<float> _colorBuffer which are to be used to draw with the vbo. There might be a problem with the libraries that I'm linking. So suggestions on what opengl extension library I should use for vbos is welcomed. I have a feeling that I'm also not loading data in correctly from the buffers... any help is appreciated.

Here is my code, I'm sure someone could notice the problem pretty easily:

[CODE]

#define NO_SDL_GLEXT
#include <GL/glew.h>
#include <SDL.h>
#include <SDL_opengl.h>

...

unsigned int FractalGenerator::_vertexHandle;
unsigned int FractalGenerator::_colorHandle;
vector<float> FractalGenerator::_vertexBuffer;
vector<float> FractalGenerator::_colorBuffer;

...

struct Color
{
float r, g, b;
};
struct Point
{
float x, y;
Color c;
};

....

for (int i = 0; i < _points.size(); i++)
{
_vertexBuffer.push_back(_points[i].x);
_vertexBuffer.push_back(_points[i].y);
_colorBuffer.push_back(_points[i].c.r);
_colorBuffer.push_back(_points[i].c.g);
_colorBuffer.push_back(_points[i].c.b);
}

...
[/CODE]

I'm getting a fault here, when I generate the the vbo for _vertexHandle

[CODE]
glGenBuffers(1, &_vertexHandle);
glBindBuffer(GL_ARRAY_BUFFER, _vertexHandle);
glBufferData(GL_ARRAY_BUFFER, _vertexBuffer.size() * sizeof(float), &_vertexBuffer.front(), GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glGenBuffers(1, &_colorHandle);
glBindBuffer(GL_ARRAY_BUFFER, _colorHandle);
glBufferData(GL_ARRAY_BUFFER, _colorBuffer.size() * sizeof(float), &_colorBuffer.front(), GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);

...

glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glScaled(_zoomFactor, _zoomFactor, 1);
glTranslated(_xOffSet, _yOffSet, 0);
glBindBuffer(GL_ARRAY_BUFFER, _vertexHandle);
glVertexPointer(2, GL_FLOAT, 0, 0L);
glBindBuffer(GL_ARRAY_BUFFER, _colorHandle);
glColorPointer(3, GL_FLOAT, 0, 0L);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glDrawArrays(GL_POINTS, 0, _vertexBuffer.size());
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glPopMatrix();
SDL_GL_SwapBuffers();
[/CODE] Edited by Jevi

Share this post


Link to post
Share on other sites
When drawing, you're binding the color buffer object but setting the vertex pointer. Sounds from your description though that you are much better of drawing pixel rectangle with glDrawPixels instead of drawing the individual pixels as points.

Share this post


Link to post
Share on other sites
[quote name='Brother Bob' timestamp='1355605046' post='5011034']
When drawing, you're binding the color buffer object but setting the vertex pointer. Sounds from your description though that you are much better of drawing pixel rectangle with glDrawPixels instead of drawing the individual pixels as points.
[/quote]

Yeah I have updated the code to use glColorPointer for the color buffer but that is not where my original problem is.

Is there any reason why my code won't get passed

glGenBuffers(1, &_vertexHandle);

Share this post


Link to post
Share on other sites
[quote name='Brother Bob' timestamp='1355612739' post='5011076']
What do you mean it won't get passed; what isn't passed to that function? Does it not generate a unique buffer handle?
[/quote]

I'm using Microsoft Visual Studio and it gives me the option to Break or Continue. This is what the message says "Unhandled exception at 0x77a215de in FractalGenerator.exe: 0xC0000005: Access violation." at that glGenBuffer line. Am I using the correct libraries for this? Im using glew for the extensions and sdl_opengl Edited by Jevi

Share this post


Link to post
Share on other sites
[quote name='Jevi' timestamp='1355614950' post='5011098']
[quote name='Brother Bob' timestamp='1355612739' post='5011076']
What do you mean it won't get passed; what isn't passed to that function? Does it not generate a unique buffer handle?
[/quote]

I'm using Microsoft Visual Studio and it gives me the option to Break or Continue. This is what the message says "Unhandled exception at 0x77a215de in FractalGenerator.exe: 0xC0000005: Access violation." at that glGenBuffer line. Am I using the correct libraries for this? Im using glew for the extensions and sdl_opengl
[/quote]

I figured it out. I did not initialize glew functions. All I needed was glewInit(): and everything worked... :) thanks!

Share this post


Link to post
Share on other sites

This topic is 1858 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Similar Content

    • By xhcao
      Does sync be needed to read texture content after access texture image in compute shader?
      My simple code is as below,
      glUseProgram(program.get());
      glBindImageTexture(0, texture[0], 0, GL_FALSE, 3, GL_READ_ONLY, GL_R32UI);
      glBindImageTexture(1, texture[1], 0, GL_FALSE, 4, GL_WRITE_ONLY, GL_R32UI);
      glDispatchCompute(1, 1, 1);
      // Does sync be needed here?
      glUseProgram(0);
      glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer);
      glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                     GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, texture[1], 0);
      glReadPixels(0, 0, kWidth, kHeight, GL_RED_INTEGER, GL_UNSIGNED_INT, outputValues);
       
      Compute shader is very simple, imageLoad content from texture[0], and imageStore content to texture[1]. Does need to sync after dispatchCompute?
    • By Jonathan2006
      My question: is it possible to transform multiple angular velocities so that they can be reinserted as one? My research is below:
      // This works quat quaternion1 = GEQuaternionFromAngleRadians(angleRadiansVector1); quat quaternion2 = GEMultiplyQuaternions(quaternion1, GEQuaternionFromAngleRadians(angleRadiansVector2)); quat quaternion3 = GEMultiplyQuaternions(quaternion2, GEQuaternionFromAngleRadians(angleRadiansVector3)); glMultMatrixf(GEMat4FromQuaternion(quaternion3).array); // The first two work fine but not the third. Why? quat quaternion1 = GEQuaternionFromAngleRadians(angleRadiansVector1); vec3 vector1 = GETransformQuaternionAndVector(quaternion1, angularVelocity1); quat quaternion2 = GEQuaternionFromAngleRadians(angleRadiansVector2); vec3 vector2 = GETransformQuaternionAndVector(quaternion2, angularVelocity2); // This doesn't work //quat quaternion3 = GEQuaternionFromAngleRadians(angleRadiansVector3); //vec3 vector3 = GETransformQuaternionAndVector(quaternion3, angularVelocity3); vec3 angleVelocity = GEAddVectors(vector1, vector2); // Does not work: vec3 angleVelocity = GEAddVectors(vector1, GEAddVectors(vector2, vector3)); static vec3 angleRadiansVector; vec3 angularAcceleration = GESetVector(0.0, 0.0, 0.0); // Sending it through one angular velocity later in my motion engine angleVelocity = GEAddVectors(angleVelocity, GEMultiplyVectorAndScalar(angularAcceleration, timeStep)); angleRadiansVector = GEAddVectors(angleRadiansVector, GEMultiplyVectorAndScalar(angleVelocity, timeStep)); glMultMatrixf(GEMat4FromEulerAngle(angleRadiansVector).array); Also how do I combine multiple angularAcceleration variables? Is there an easier way to transform the angular values?
    • By dpadam450
      I have this code below in both my vertex and fragment shader, however when I request glGetUniformLocation("Lights[0].diffuse") or "Lights[0].attenuation", it returns -1. It will only give me a valid uniform location if I actually use the diffuse/attenuation variables in the VERTEX shader. Because I use position in the vertex shader, it always returns a valid uniform location. I've read that I can share uniforms across both vertex and fragment, but I'm confused what this is even compiling to if this is the case.
       
      #define NUM_LIGHTS 2
      struct Light
      {
          vec3 position;
          vec3 diffuse;
          float attenuation;
      };
      uniform Light Lights[NUM_LIGHTS];
       
       
    • By pr033r
      Hello,
      I have a Bachelor project on topic "Implenet 3D Boid's algorithm in OpenGL". All OpenGL issues works fine for me, all rendering etc. But when I started implement the boid's algorithm it was getting worse and worse. I read article (http://natureofcode.com/book/chapter-6-autonomous-agents/) inspirate from another code (here: https://github.com/jyanar/Boids/tree/master/src) but it still doesn't work like in tutorials and videos. For example the main problem: when I apply Cohesion (one of three main laws of boids) it makes some "cycling knot". Second, when some flock touch to another it scary change the coordination or respawn in origin (x: 0, y:0. z:0). Just some streng things. 
      I followed many tutorials, change a try everything but it isn't so smooth, without lags like in another videos. I really need your help. 
      My code (optimalizing branch): https://github.com/pr033r/BachelorProject/tree/Optimalizing
      Exe file (if you want to look) and models folder (for those who will download the sources):
      http://leteckaposta.cz/367190436
      Thanks for any help...

    • By Andrija
      I am currently trying to implement shadow mapping into my project , but although i can render my depth map to the screen and it looks okay , when i sample it with shadowCoords there is no shadow.
      Here is my light space matrix calculation
      mat4x4 lightViewMatrix; vec3 sun_pos = {SUN_OFFSET * the_sun->direction[0], SUN_OFFSET * the_sun->direction[1], SUN_OFFSET * the_sun->direction[2]}; mat4x4_look_at(lightViewMatrix,sun_pos,player->pos,up); mat4x4_mul(lightSpaceMatrix,lightProjMatrix,lightViewMatrix); I will tweak the values for the size and frustum of the shadow map, but for now i just want to draw shadows around the player position
      the_sun->direction is a normalized vector so i multiply it by a constant to get the position.
      player->pos is the camera position in world space
      the light projection matrix is calculated like this:
      mat4x4_ortho(lightProjMatrix,-SHADOW_FAR,SHADOW_FAR,-SHADOW_FAR,SHADOW_FAR,NEAR,SHADOW_FAR); Shadow vertex shader:
      uniform mat4 light_space_matrix; void main() { gl_Position = light_space_matrix * transfMatrix * vec4(position, 1.0f); } Shadow fragment shader:
      out float fragDepth; void main() { fragDepth = gl_FragCoord.z; } I am using deferred rendering so i have all my world positions in the g_positions buffer
      My shadow calculation in the deferred fragment shader:
      float get_shadow_fac(vec4 light_space_pos) { vec3 shadow_coords = light_space_pos.xyz / light_space_pos.w; shadow_coords = shadow_coords * 0.5 + 0.5; float closest_depth = texture(shadow_map, shadow_coords.xy).r; float current_depth = shadow_coords.z; float shadow_fac = 1.0; if(closest_depth < current_depth) shadow_fac = 0.5; return shadow_fac; } I call the function like this:
      get_shadow_fac(light_space_matrix * vec4(position,1.0)); Where position is the value i got from sampling the g_position buffer
      Here is my depth texture (i know it will produce low quality shadows but i just want to get it working for now):
      sorry because of the compression , the black smudges are trees ... https://i.stack.imgur.com/T43aK.jpg
      EDIT: Depth texture attachment:
      glTexImage2D(GL_TEXTURE_2D, 0,GL_DEPTH_COMPONENT24,fbo->width,fbo->height,0,GL_DEPTH_COMPONENT,GL_FLOAT,NULL); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, fbo->depthTexture, 0);
  • Popular Now