Why doesn't glCopyTexSubImage2D copy my square correctly?

Question

here is the output: http://i43.tinypic.com/9a5zyx.png if things were working the way i wanted, the colors in the left square would match the colors in the right square. thanks for any help regarding the subject

#include <gl/glfw.h>

const char* title="test";
GLuint img;
unsigned int w=64,h=64;
int screenwidth,screenheight;

void enable2d()
{
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();

    glViewport(0,0,screenwidth,screenheight);
    glOrtho(0,screenwidth,screenheight,0,-1,1);

    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();

    glPushAttrib(GL_DEPTH_BUFFER_BIT|GL_LIGHTING_BIT);
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_LIGHTING);

    glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
}

void drawmytex()
{
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,img);
    glBegin(GL_QUADS);
    glTexCoord2i(0,0);
    glVertex2i(0,0);
    glTexCoord2i(1,0);
    glVertex2i(w,0);
    glTexCoord2i(1,1);
    glVertex2i(w,h);
    glTexCoord2i(0,1);
    glVertex2i(0,h);
    glEnd();
    glDisable(GL_TEXTURE_2D);
}

void drawquad(int x,int y)
{
    glBegin(GL_QUADS);
    glColor3f(0.0f,1.0f,0.0f);
    glVertex2i(x,y);
    glColor3f(1.0f,0.0f,1.0f);
    glVertex2i(x+w,y);
    glColor3f(0.0f,1.0f,1.0f);
    glVertex2i(x+w,y+h);
    glColor3f(0.0f,0.0f,1.0f);
    glVertex2i(x,y+h);
    glEnd();
}

void texcopy()
{
    if (!glIsTexture(img))
        glDeleteTextures(1,&img);
    glGenTextures(1,&img);
    glBindTexture(GL_TEXTURE_2D,img);
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,w,h,0,GL_RGBA,GL_UNSIGNED_BYTE,0);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0,w,h,0,-1,1);
    glViewport(0,0,w,h);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    drawquad(0,0);

    glBindTexture(GL_TEXTURE_2D,img);
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
    //glCopyTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,0,0,w,h,0);
    glCopyTexSubImage2D(GL_TEXTURE_2D,0,0,0,0,0,w,h);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0,screenwidth,screenheight,0,-1,1);
    glViewport(0,0,screenwidth,screenheight);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

int main()
{
    int running;

    glfwInit();

    running=glfwOpenWindow(640,480,0,0,0,0,0,0,GLFW_WINDOW);
    if (!running)
    {
        glfwTerminate();
        return 0;
    }


    glfwSetWindowTitle(title);
    glfwEnable(GLFW_STICKY_KEYS);
    glfwGetWindowSize(&screenwidth,&screenheight);

    enable2d();
    texcopy();

    do
    {
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
        glLoadIdentity();

        drawquad(64,0);
        drawmytex();

        glfwSwapBuffers();
        running=!glfwGetKey(GLFW_KEY_ESC)&&glfwGetWindowParam(GLFW_OPENED);
        GLenum error=glGetError();
        if (error!=GL_NO_ERROR)running=error;
        glfwSleep(.017);
    }
    while (running==1);

    glDeleteTextures(1,&img);

    glfwTerminate();
    return running;
}

rotoglup rotoglup · Accepted Answer · 2009-03-13T17:32:08

Try adding 'glColor3f(1,1,1);' in your 'drawmytex' function. I suspect that your texture is modulated (multiplied) with the current color, if so, the problem is not the texture copy but the way you display it.

Why doesn't glCopyTexSubImage2D copy my square correctly?

1 Answers