I am using OpenGL, I can load tga files properly, but for some reason when i render jpg files, i do not see them correctly.
This is what the image is supposed to look like--
And this is what it looks like.. why is it stretched? is it because of the coordinates?
Here is the code i am using for drawing.
void Renderer::DrawJpg(GLuint tex, int xi, int yq, int width, int height) const
{
glBindTexture(GL_TEXTURE_2D, tex);
glBegin(GL_QUADS);
glTexCoord2i(0, 0); glVertex2i(0+xi, 0+xi);
glTexCoord2i(0, 1); glVertex2i(0+xi, height+xi);
glTexCoord2i(1, 1); glVertex2i(width+xi, height+xi);
glTexCoord2i(1, 0); glVertex2i(width+xi, 0+xi);
glEnd();
}
This is how i am loading the image...
imagename=s;
ILboolean success;
ilInit();
ilGenImages(1, &id);
ilBindImage(id);
success = ilLoadImage((const ILstring)imagename.c_str());
if (success)
{
success = ilConvertImage(IL_RGB, IL_UNSIGNED_BYTE); /* Convert every colour component into
unsigned byte. If your image contains alpha channel you can replace IL_RGB with IL_RGBA */
if (!success)
{
printf("image conversion failed.");
}
glGenTextures(1, &id);
glBindTexture(GL_TEXTURE_2D, id);
width = ilGetInteger(IL_IMAGE_WIDTH);
height = ilGetInteger(IL_IMAGE_HEIGHT);
glTexImage2D(GL_TEXTURE_2D, 0, ilGetInteger(IL_IMAGE_BPP), ilGetInteger(IL_IMAGE_WIDTH),
ilGetInteger(IL_IMAGE_HEIGHT), 0, ilGetInteger(IL_IMAGE_FORMAT), GL_UNSIGNED_BYTE,
ilGetData());
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); // Linear Filtered
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); // Linear Filtered
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
I probably should mention this, but some images did get rendered properly, I thought it was because width != height. But that is not the case, images with width != height also get loaded fine. But for other images i still get this problem.
You probably need to call
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
before uploading the texture data with glTexImage2D
.
From the reference pages:
GL_UNPACK_ALIGNMENT
Specifies the alignment requirements for the start of each pixel row in memory. The allowable values are 1 (byte-alignment), 2 (rows aligned to even-numbered bytes), 4 (word-alignment), and 8 (rows start on double-word boundaries).
The default value for the alignment is 4 and your image loading library probably returns pixel data with byte-aligned rows, which explains why some of your images look OK (when the width is a multiple of four).