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taby

OpenGL AMD 6310 GLSL/FBO texture copy issue

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I'm using OpenGL 2.0 and an FBO to copy some data from an RGBA texture to an RGB texture, and I ran into an issue where sometimes it "corrupts" the first few lowest order bits of some of the pixel components during the copy.

 

The texture copy is broken up into several steps, and I'm resizing the FBO.

 

At first I thought perhaps it was a problem related to the way that I was resizing the FBO, or with the way the the texture is being sampled, but the problem doesn't always occur, and when it does, it never occurs for every pixel copied nor does it ever occur for all of the components of each problematic pixel. In other words, it seems nearly random, except that it is indeed deterministic insomuch that the same error(s) occur if the same input float values are used during each run of the program.

 

Also, the problem never, ever occurs if I always use an FBO size of 1x1 (which is kind of misleading to know, because it made me think that it was a sampling issue, but, again, that is probably not the case since not every component of every problematic pixel is "corrupted"). Unfortunately, using an FBO size of 1x1 is absolutely useless in the real world where I'm going to be copying a texture containing anything more than a few pixels.

 

The problem happens on Windows 7 and Ubuntu, and the problem happens when I use MSVC++ or g++'s std rand() or Mersenne Twister to generate the input texture values (not that how I generate the values should matter, since copy operations are by definition independent of how the data to be copied was generated beforehand) .

 

I wrote a test program (see code below) where nothing changes between runs of the program other than the input texture values.

 

Does anyone have an AMD 6310 (or any other kind of hardware, really) that they can run this test program on? You'll have to run it a few times, as sometimes it produces an error, and sometimes it does not. I'm just curious if it ever produces the error on your hardware. I just can't spot the pattern, and my naive thinking is that this should either work all of the time, or never -- not so sporadically.

 

I'm also totally wiling to accept that it might, in the end, have something to do with the way that I'm using OpenGL to do the copy. This would be relieving actually, since it would mean that there's an easy and reliable solution. I hope this is the case.

 

I probably have some extraneous calls to glTexParameteri in there somewhere, but I was trying the "better safe than sorry" method while working on this test program.

 

In any case, the problem results in some of the pixel components having error that's on the order of like ~1e-8. Yes, that's a very small error, but it's totally unacceptable for what I'm doing.

 

#include <iostream>
using std::cout;
using std::endl;

#include <iomanip>
using std::ios_base;
using std::setprecision;
using std::fixed;

#include <vector>
using std::vector;

#include <string>
using std::string;

#include <utility>
using std::pair;

#include <cmath>
#include <cstdlib> // MSVC++ chokes if you don't include this before glut.h
#include <ctime>

#include <GL/glew.h>
#include <GL/glut.h>

// Automatically link in the GLUT and GLEW libraries if compiling on MSVC++
#ifdef _MSC_VER
    #pragma comment(lib, "glew32")
    #pragma comment(lib, "glut32")
#endif



float dist(float a, float b);
bool initialize_fragment_shader(const string &fragment_shader_code, GLint &shader, string &error);
void get_chunk_sizes(const size_t num_pixels, vector< pair<size_t, size_t> > &chunk_sizes, const bool force_1x1_chunks, const bool force_square_chunks = false);
string float_bits_string(const float f);

int main(int argc, char **argv)
{
    // This program uses an FBO and a fragment shader to copy RGBA pixels from an input array into an RGB output array.
    // It breaks up the entire pixel copy process into many smaller chunks of a varying number of pixels per chunk.
    // See line 165 to change the number of pixels in the array (right now it's hard-coded to be 7 pixels total).

    // If the chunk sizes are forced to be 1x1 pixels, then there are never any problems with the copy.
    // See line 186 to change whether the chunks are forced to be 1x1 pixels or not (right not they are not being forced as such).
    //
    // If the chunk sizes are not forced to be 1x1 pixels, then almost all of the time (but not quite always)
    // there is a small problem with at least one component of one of the pixels during the copy:
    //
    // The copy is off by a small, non-zero value of practically constant magnitude (on the order of ~1e-8).
    //
    // Since the values of the pixel components are the only thing that change between runs of the program,
    // the problem seems to be entirely dependent on the values of the pixel components themselves. This is totally
    // unexpected -- it should always work or always fail to the same degree, regardless of the pixel component values.
    // While looking at the bit patterns of the problematic pixel component values, it seems that it is always only the
    // first three to five lowest order bits that do not get copied successfully.
    //
    // Note that if the values of the pixel components do not change between runs, then the same errors occur,
    // and so the problem seems to be entirely deterministic. Right now the components are set via PRNG, and are done in a way
    // so that all of the bits of precision are used (see lines 173 - 176).
    // See line 86 to alter the PRNG seed.



// 1) Initialize pseudo-random number generator.
    srand(time(0)); // srand(0);



// 2) Initialize OpenGL and related objects.
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGBA);
    GLint glut_window_handle = glutCreateWindow("");

    if(! ( GLEW_OK == glewInit() &&
           GLEW_VERSION_2_0 &&
           GLEW_ARB_framebuffer_object &&
           GLEW_ARB_texture_rectangle ) )
    {
        return -1;
    }

    GLint shader_handle = 0;
    GLuint fbo_handle = 0;
    GLuint tex_fbo_handle = 0;
    GLuint tex_in_handle = 0;
    GLuint tex_out_handle = 0;
    const GLint tex_in_internal_format = GL_RGBA32F_ARB;
    const GLint tex_in_format = GL_RGBA;
    const GLint tex_out_internal_format = GL_RGB32F_ARB;
    const GLint tex_out_format = GL_RGB;
    const GLint var_type = GL_FLOAT;

    string code;
    code += "#version 110\n";
    code += "uniform sampler2D input_tex;\n";
    code += "void main(void)\n";
    code += "{\n";
    code += "    vec4 p = texture2D(input_tex, gl_TexCoord[0].st);\n";
    code += "    gl_FragData[0].rgb = vec3(p.xyz);\n";
    code += "}\n";

    string error;

    if(false == initialize_fragment_shader(code, shader_handle, error))
    {
        cout << error << endl;
        return -2;
    }

    glGenTextures(1, &tex_in_handle);
    glBindTexture(GL_TEXTURE_2D, tex_in_handle);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glGenTextures(1, &tex_out_handle);
    glBindTexture(GL_TEXTURE_2D, tex_out_handle);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glGenFramebuffersEXT(1, &fbo_handle);
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo_handle);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glGenTextures(1, &tex_fbo_handle);
    glBindTexture(GL_TEXTURE_2D, tex_fbo_handle);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glUseProgram(shader_handle);
    glUniform1i(glGetUniformLocation(shader_handle, "input_tex"), 0); // Use texture 0.



// 3) Set up input -- an array of RGBA float pixels with pseudorandom values.
    size_t num_pixels = 7; // = rand() % 50 + 1;
    size_t num_input_channels = 4;
    vector<float> input(num_pixels*num_input_channels, 0);

    for(size_t i = 0; i < num_pixels; i++)
    {
        size_t input_index = i*num_input_channels;
        
        input[input_index + 0] = static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
        input[input_index + 1] = static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
        input[input_index + 2] = static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
        input[input_index + 3] = static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
    }



// 4) Break up processing of input into chunks.
    vector< pair<size_t, size_t> > chunks;



#ifdef FORCE_1x1_CHUNKS
    get_chunk_sizes(num_pixels, chunks, true, true);
#else
    get_chunk_sizes(num_pixels, chunks, false, true);
#endif



    size_t num_pixels_remaining = num_pixels;

    size_t num_output_channels = 3;
    vector<float> output(num_pixels*num_output_channels, 0);

    for(size_t i = 0; i < chunks.size(); i++)
    {
        cout << "Pixels remaining: " << num_pixels_remaining << ", processing chunk size: " << chunks.first << " x " << chunks.second << " = " << chunks.first*chunks.second << endl;

        const size_t tex_size_x = chunks.first;
        const size_t tex_size_y = chunks.second;
        const size_t index = num_pixels - num_pixels_remaining;
        const size_t input_index = index*num_input_channels;
        const size_t output_index = index*num_output_channels;

        // Set the FBO size to match the current chunk size.
        glBindTexture(GL_TEXTURE_2D, tex_fbo_handle);
        glTexImage2D(GL_TEXTURE_2D, 0, tex_out_internal_format, tex_size_x, tex_size_y, 0, tex_out_format, var_type, 0);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, tex_fbo_handle, 0);

        // Write to GPU memory.
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, tex_in_handle);
        glTexImage2D(GL_TEXTURE_2D, 0, tex_in_internal_format, tex_size_x, tex_size_y, 0, tex_in_format, var_type, &input[input_index]);

        // Calculate by "drawing".
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0, 1, 0, 1, 0, 1);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        glViewport(0, 0, tex_size_x, tex_size_y);

        glBegin(GL_QUADS);
            glTexCoord2f(0, 1);    glVertex2f(0, 1);
            glTexCoord2f(0, 0);    glVertex2f(0, 0);
            glTexCoord2f(1, 0); glVertex2f(1, 0);
            glTexCoord2f(1, 1);    glVertex2f(1, 1);
        glEnd();

        // Read from GPU memory.
        glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
        glReadPixels(0, 0, tex_size_x, tex_size_y, tex_out_format, var_type, &output[output_index]);

        num_pixels_remaining -= tex_size_x*tex_size_y;
    }



// 5) Analyze largest distance between input and output -- it should be zero, but it is not zero
//    if the chunk sizes are not forced to be 1x1.
    float largest_dist = 0;
    cout << setprecision(18);

    cout << endl << "Comparing input and output: " << endl;

    for(size_t i = 0; i < num_pixels; i++)
    {
        size_t input_index = i*num_input_channels;
        size_t output_index = i*num_output_channels;

        float dist0 = dist(input[input_index + 0], output[output_index + 0]);
        float dist1 = dist(input[input_index + 1], output[output_index + 1]);
        float dist2 = dist(input[input_index + 2], output[output_index + 2]);

        if(dist0 > largest_dist)
            largest_dist = dist0;

        if(dist1 > largest_dist)
            largest_dist = dist1;

        if(dist2 > largest_dist)
            largest_dist = dist2;

        if(dist0 != 0)
        {
            cout << endl;
            cout << "**** Copy error at pixel " << i + 1  << " first component" << endl;
            cout << "\tInput:  " << input[input_index + 0] << '\n' << "\tOutput: " << output[output_index + 0] << endl;
            cout << "\tInput (as bits):  " << float_bits_string(input[input_index + 0]) << '\n' << "\tOutput (as bits): " << float_bits_string(output[output_index + 0]) << endl;
            cout << endl;
        }
        else
        {
            cout << "OK at pixel " << i + 1  << " first component" << endl;
//            cout << "\tInput:  " << input[input_index + 0] << '\n' << "\tOutput: " << output[output_index + 0] << endl;
        }

        if(dist1 != 0)
        {
            cout << endl;
            cout << "**** Copy error at pixel " << i + 1 << " second component" << endl;
            cout << "\tInput:  " << input[input_index + 1] << '\n' << "\tOutput: " << output[output_index + 1] << endl;
            cout << "\tInput (as bits):  " << float_bits_string(input[input_index + 1]) << '\n' << "\tOutput (as bits): " << float_bits_string(output[output_index + 1]) << endl;
            cout << endl;
        }
        else
        {
            cout << "OK at pixel " << i + 1 << " second component" << endl;
//            cout << "\tInput:  " << input[input_index + 1] << '\n' << "\tOutput: " << output[output_index + 1] << endl;
        }

        if(dist2 != 0)
        {
            cout << endl;
            cout << "**** Copy error at pixel " << i + 1 << " third component" << endl;
            cout << "\tInput:  " << input[input_index + 2] << '\n' << "\tOutput: " << output[output_index + 2] << endl;
            cout << "\tInput (as bits):  " << float_bits_string(input[input_index + 2]) << '\n' << "\tOutput (as bits): " << float_bits_string(output[output_index + 2]) << endl;
            cout << endl;
        }
        else
        {
            cout << "OK at pixel " << i + 1 << " third component" << endl;
//            cout << "\tInput:  " << input[input_index + 2] << '\n' << "\tOutput: " << output[output_index + 2] << endl;
        }

    }

    if(0 != largest_dist)
        cout << "\nLargest copy error: " << largest_dist << endl;
    else
        cout << "\nNo copy errors." << endl;



// 6) Cleanup OpenGL and related objects.
    glDeleteTextures(1, &tex_in_handle);
    glDeleteTextures(1, &tex_out_handle);
    glDeleteTextures(1, &tex_fbo_handle);
    glDeleteFramebuffersEXT(1, &fbo_handle);
    glUseProgram(0);
    glDeleteProgram(shader_handle);
    glutDestroyWindow(glut_window_handle);

    return 0;
}

float dist(float a, float b)
{
    return fabsf(b - a);
}

bool initialize_fragment_shader(const string &fragment_shader_code, GLint &shader, string &error)
{
    error = "";

    // Compile shader.
    const char *cch = 0;
    GLint status = GL_FALSE;
    GLint frag = glCreateShader(GL_FRAGMENT_SHADER);

    glShaderSource(frag, 1, &(cch = fragment_shader_code.c_str()), 0);
    glCompileShader(frag);
    glGetShaderiv(frag, GL_COMPILE_STATUS, &status);

    if(GL_FALSE == status)
    {
        error = "Fragment shader compile error.\n";
        vector<GLchar> buf(4096, '\0');
        glGetShaderInfoLog(frag, 4095, 0, &buf[0]);

        for(size_t i = 0; i < buf.size(); i++)
            if(0 != buf)
                error += buf;

        error += '\n';

        return false;
    }

    // Link to get final shader.
    shader = glCreateProgram();
    glAttachShader(shader, frag);
    glLinkProgram(shader);
    glGetProgramiv(shader, GL_LINK_STATUS, &status);

    if(GL_FALSE == status)
    {
        error = "Program link error.\n";
        vector<GLchar> buf(4096, '\0');
        glGetShaderInfoLog(shader, 4095, 0, &buf[0]);

        for(size_t i = 0; i < buf.size(); i++)
            if(0 != buf)
                error += buf;

        error += '\n';

        glDetachShader(shader, frag);
        glDeleteShader(frag);
        return false;
    }

    // Cleanup.
    glDetachShader(shader, frag);
    glDeleteShader(frag);

    return true;
}

void get_chunk_sizes(const size_t num_pixels, vector< pair<size_t, size_t> > &chunk_sizes, const bool force_1x1_chunks, const bool force_square_chunks)
{
    chunk_sizes.clear();

    size_t num_pixels_remaining = num_pixels;
    GLint max_tex_size = 0;

    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max_tex_size);

    size_t curr_tex_x = max_tex_size;
    size_t curr_tex_y = max_tex_size;

    if(true == force_1x1_chunks)
        curr_tex_x = curr_tex_y = 1;

    while(0 < num_pixels_remaining)
    {
        if(num_pixels_remaining < curr_tex_x*curr_tex_y)
        {
            if(true == force_square_chunks)
            {
                curr_tex_x /= 2;
                curr_tex_y /= 2;
            }
            else
            {
                if(curr_tex_x == curr_tex_y)
                    curr_tex_y /= 2;
                else
                    curr_tex_x /= 2;
            }
        }
        else
        {
            pair<size_t, size_t> p(curr_tex_x, curr_tex_y);
            chunk_sizes.push_back(p);
            num_pixels_remaining -= curr_tex_x*curr_tex_y;
        }
    }
}

string float_bits_string(const float f)
{
    long unsigned int bit_mask = 1;
    long unsigned int intval = *(long unsigned int*)&f;

    string bits;

    for(size_t i = 0; i < 32; i++, bit_mask <<= 1)
    {
        if(intval & bit_mask)
            bits += '1';
        else
            bits += '0';
    }

    bits = string(bits.rbegin(), bits.rend());

    return bits;
}
 
Edited by taby

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Problem doesn't occur on Intel GPU. Much obliged for the help.

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      1) I render text using atlas with VBO containing x/y/u/v of every digit in the atlas (calculated basing on x/y/z/width/height/xoffset/yoffset/xadvance data in binary .fnt format file, screenshot 1). I generated a Comic Sans MS with 32 size and times new roman with size 12 (screenshot 2 and 3). The first issue is the font looks horrible when rescaling. I guess it is because i am using fixed -1 to 1 screen space coords. This is where ortho matrix should be used, right?
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      3) The game is 3D but i have to go 2D to render static gui elements over the scene - and i want to do it properly! At the moment i am using matrix 3x3 for 2d transformations and vec3 for all kinds of coordinates. In shaders tho i technically still IS 3D. I have to set all 4 x y z w of the gl_Position while it would be much much more conventient to... just do the maths in 2d space. Can i achieve it somehow?
      4) Text again. I am kind of confused what is the reason of artifacts in Times New Roman font displaying (screenshot 1). I render from left to right, letter after letter. You can clearly see that letters on the right (so the ones rendered after ones on the left are covered by the previous one). I was toying around with blending options but no luck. I do not support kerning at the moment but that's definitely not the cause of error. The display of the small font looks dirty aliased too. I am knd of confused how to interpret the integer data and how should be scaled/adapted to the screen view. Is it just store the data as constant size and again - use ortho matrix?
      Thanks in advance for all your ideas and suggestions!
      https://i.imgur.com/4rd1VC3.png
      https://i.imgur.com/uHrSXfe.png
      https://i.imgur.com/xRTffPn.png
    • By plz717
      Hello, everyone! I hope my problem isn't too 'beginnerish'. I'm doing research on motion synthesis now, trying to implement the Deep Mimic paper (DeepMimic) by BINPENG XUE, in this paper, I need to first retarget character A's motion to another character B to make the reference motion clips for character B, since we don't have character B‘s reference motion. The most important thing is that in the paper, the author copied character A's joint's rotation with respective to joint's local coordinate system (not the parent) to character B. In my personal understanding, the joint's rotation with respective to joint's local coordinate system is something like that in the attached photo, where for the Elbow joint, i need to get the Elbow's rotation in the elbow's local coordinate system (i'm very grateful for you to share your ideas if i have misunderstanding about it 🙂)
      I have searched many materials on the internet about how to extract the local joint's information from FBX, the most relative one i found is the pivot rotation( and geometric transformation, object offset transformation). I'm a beginner in computer graphics, and i'm confused about whether the pivot rotation( or geometric transformation, object offset transformation) is exactly the joint's local rotation i'm seeking? I hope someone that have any ideas can help me, I'd be very grateful for any pointers in the right direction. Thanks in advance! 

    • By nOoNEE
      hello guys , i have some questions  what does glLinkProgram  and  glBindAttribLocation do?  i searched but there wasnt any good resource 
    • By owenjr
      Hi, I'm a Multimedia Engineering student. I am about to finish my dergree and I'm already thinking about what topic to cover in my final college project.
      I'm interested in the procedural animation with c++ and OpenGL of creatures, something like a spider for example. Can someone tell me what are the issues I should investigate to carry it out? I understand that it has some dependence on artificial intelligence but I do not know to what extent. Can someone help me to find information about it? Thank you very much.
       
      Examples: 
      - Procedural multi-legged walking animation
      - Procedural Locomotion of Multi-Legged Characters in Dynamic Environments
    • By Lewa
      So, i'm still on my quest to unterstanding the intricacies of HDR and implementing this into my engine. Currently i'm at the step to implementing tonemapping. I stumbled upon this blogposts:
      http://filmicworlds.com/blog/filmic-tonemapping-operators/
      http://frictionalgames.blogspot.com/2012/09/tech-feature-hdr-lightning.html
      and tried to implement some of those mentioned tonemapping methods into my postprocessing shader.
      The issue is that none of them creates the same results as shown in the blogpost which definitely has to do with the initial range in which the values are stored in the HDR buffer. For simplicity sake i store the values between 0 and 1 in the HDR buffer (ambient light is 0.3, directional light is 0.7)
      This is the tonemapping code:
      vec3 Uncharted2Tonemap(vec3 x) { float A = 0.15; float B = 0.50; float C = 0.10; float D = 0.20; float E = 0.02; float F = 0.30; return ((x*(A*x+C*B)+D*E)/(x*(A*x+B)+D*F))-E/F; } This is without the uncharted tonemapping:
      This is with the uncharted tonemapping:
      Which makes the image a lot darker.
      The shader code looks like this:
      void main() { vec3 color = texture2D(texture_diffuse, vTexcoord).rgb; color = Uncharted2Tonemap(color); //gamma correction (use only if not done in tonemapping code) color = gammaCorrection(color); outputF = vec4(color,1.0f); } Now, from my understanding is that tonemapping should bring the range down from HDR to 0-1.
      But the output of the tonemapping function heavily depends on the initial range of the values in the HDR buffer. (You can't expect to set the sun intensity the first time to 10 and the second time to 1000 and excpect the same result if you feed that into the tonemapper.) So i suppose that this also depends on the exposure which i have to implement?
      To check this i plotted the tonemapping curve:
      You can see that the curve goes only up to around to a value of 0.21 (while being fed a value of 1) and then basically flattens out. (which would explain why the image got darker.)
       
      My guestion is: In what range should the values in the HDR buffer be which then get tonemapped? Do i have to bring them down to a range of 0-1 by multiplying with the exposure?
      For example, if i increase the values of the light by 10 (directional light would be 7 and ambient light 3) then i would need to divide HDR values by 10 in order to get a value range of 0-1 which then could be fed into the tonemapping curve. Is that correct?
    • By nOoNEE
      i am reading this book : link
      in the OpenGL Rendering Pipeline section there is a picture like this: link
      but the question is this i dont really understand why it is necessary to turn pixel data in to fragment and then fragment into pixel could please give me a source or a clear Explanation that why it is necessary ? thank you so mu
       
       
    • By Inbar_xz
      I'm using the OPENGL with eclipse+JOGL.
      My goal is to create movement of the camera and the player.
      I create main class, which create some box in 3D and hold 
      an object of PlayerAxis.
      I create PlayerAxis class which hold the axis of the player.
      If we want to move the camera, then in the main class I call to 
      the func "cameraMove"(from PlayerAxis) and it update the player axis.
      That's work good.
      The problem start if I move the camera on 2 axis, 
      for example if I move with the camera right(that's on the y axis)
      and then down(on the x axis) -
      in some point the move front is not to the front anymore..
      In order to move to the front, I do
      player.playerMoving(0, 0, 1);
      And I learn that in order to keep the front move, 
      I need to convert (0, 0, 1) to the player axis, and then add this.
      I think I dont do the convert right.. 
      I will be glad for help!

      Here is part of my PlayerAxis class:
       
      //player coordinate float x[] = new float[3]; float y[] = new float[3]; float z[] = new float[3]; public PlayerAxis(float move_step, float angle_move) { x[0] = 1; y[1] = 1; z[2] = -1; step = move_step; angle = angle_move; setTransMatrix(); } public void cameraMoving(float angle_step, String axis) { float[] new_x = x; float[] new_y = y; float[] new_z = z; float alfa = angle_step * angle; switch(axis) { case "x": new_z = addVectors(multScalar(z, COS(alfa)), multScalar(y, SIN(alfa))); new_y = subVectors(multScalar(y, COS(alfa)), multScalar(z, SIN(alfa))); break; case "y": new_x = addVectors(multScalar(x, COS(alfa)), multScalar(z, SIN(alfa))); new_z = subVectors(multScalar(z, COS(alfa)), multScalar(x, SIN(alfa))); break; case "z": new_x = addVectors(multScalar(x, COS(alfa)), multScalar(y, SIN(alfa))); new_y = subVectors(multScalar(y, COS(alfa)), multScalar(x, SIN(alfa))); } x = new_x; y = new_y; z = new_z; normalization(); } public void playerMoving(float x_move, float y_move, float z_move) { float[] move = new float[3]; move[0] = x_move; move[1] = y_move; move[2] = z_move; setTransMatrix(); float[] trans_move = transVector(move); position[0] = position[0] + step*trans_move[0]; position[1] = position[1] + step*trans_move[1]; position[2] = position[2] + step*trans_move[2]; } public void setTransMatrix() { for (int i = 0; i < 3; i++) { coordiTrans[0][i] = x[i]; coordiTrans[1][i] = y[i]; coordiTrans[2][i] = z[i]; } } public float[] transVector(float[] v) { return multiplyMatrixInVector(coordiTrans, v); }  
      and in the main class i have this:
       
      public void keyPressed(KeyEvent e) { if (e.getKeyCode()== KeyEvent.VK_ESCAPE) { System.exit(0); //player move } else if (e.getKeyCode()== KeyEvent.VK_W) { //front //moveAmount[2] += -0.1f; player.playerMoving(0, 0, 1); } else if (e.getKeyCode()== KeyEvent.VK_S) { //back //moveAmount[2] += 0.1f; player.playerMoving(0, 0, -1); } else if (e.getKeyCode()== KeyEvent.VK_A) { //left //moveAmount[0] += -0.1f; player.playerMoving(-1, 0, 0); } else if (e.getKeyCode()== KeyEvent.VK_D) { //right //moveAmount[0] += 0.1f; player.playerMoving(1, 0, 0); } else if (e.getKeyCode()== KeyEvent.VK_E) { //moveAmount[0] += 0.1f; player.playerMoving(0, 1, 0); } else if (e.getKeyCode()== KeyEvent.VK_Q) { //moveAmount[0] += 0.1f; player.playerMoving(0, -1, 0); //camera move } else if (e.getKeyCode()== KeyEvent.VK_I) { //up player.cameraMoving(1, "x"); } else if (e.getKeyCode()== KeyEvent.VK_K) { //down player.cameraMoving(-1, "x"); } else if (e.getKeyCode()== KeyEvent.VK_L) { //right player.cameraMoving(-1, "y"); } else if (e.getKeyCode()== KeyEvent.VK_J) { //left player.cameraMoving(1, "y"); } else if (e.getKeyCode()== KeyEvent.VK_O) { //right round player.cameraMoving(-1, "z"); } else if (e.getKeyCode()== KeyEvent.VK_U) { //left round player.cameraMoving(1, "z"); } }  
      finallt found it.... i confused with the transformation matrix row and col. thanks anyway!
    • By Lewa
      So, i'm currently trying to implement an SSAO shader from THIS tutorial and i'm running into a few issues here.
      Now, this SSAO method requires view space positions and normals. I'm storing the normals in my deferred renderer in world-space so i had to do a conversion and reconstruct the position from the depth buffer.
      And something there goes horribly wrong (which has probably to do with worldspace to viewspace transformations).
      (here is the full shader source code if someone wants to take a look at it)
      Now, i suspect that the normals are the culprit.
      vec3 normal = ((uNormalViewMatrix*vec4(normalize(texture2D(sNormals, vTexcoord).rgb),1.0)).xyz); "sNormals" is a 2D texture which stores the normals in world space in a RGB FP16 buffer.
      Now i can't use the camera viewspace matrix to transform the normals into viewspace as the cameras position isn't set at (0,0,0), thus skewing the result.
      So what i did is to create a new viewmatrix specifically for this normal without the position at vec3(0,0,0);
      //"camera" is the camera which was used for rendering the normal buffer renderer.setUniform4m(ressources->shaderSSAO->getUniform("uNormalViewMatrix"), glmExt::createViewMatrix(glm::vec3(0,0,0),camera.getForward(),camera.getUp())//parameters are (position,forwardVector,upVector) ); Though i have the feeling this is the wrong approach. Is this right or is there a better/correct way of transforming a world space normal into viewspace?
    • By HawkDeath
      Hi,
      I'm trying mix two textures using own shader system, but I have a problem (I think) with uniforms.
      Code: https://github.com/HawkDeath/shader/tree/test
      To debug I use RenderDocs, but I did not receive good results. In the first attachment is my result, in the second attachment is what should be.
      PS. I base on this tutorial https://learnopengl.com/Getting-started/Textures.


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