Ndtyjky

I don't think this is a problem with the image I'm loading. The image resolution is 256x256 so it's not the power of 2 issue. I've looked at other segfaults people got with glTexImage2D and the segfault still can't seem to go away. Sorry that the code isn't in C/C++ (i don't think this is the problem either) but it should still be easy to understand.

let surface = sdlimage.load("image.png") # equivalent to IMG_Load call in C

if surface.isNil:

  echo "Image couldn't be loaded: ", sdl2.getError()

  quit 1



glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)

glEnable(GL_BLEND)



var tex: cuint

glGenTextures(1, addr tex)

glBindTexture(GL_TEXTURE_2D, tex)

glPixelStorei(GL_UNPACK_ALIGNMENT, 1)

glPixelStorei(GL_UNPACK_ROW_LENGTH, surface.pitch)

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA.GLint, surface.w.GLsizei, surface.h.GLsizei, 0, GL_RGBA, GL_UNSIGNED_BYTE, surface.pixels) # segfault

UPDATE:

I managed to get it to not segfault thanks to user1118321's answer (I checked the pixel format and saw that SDL used a "indexed" format, which I saw another user said was the problem when they fixed this issue for theirselves. Seems like creating a new surface is the right solution), but now it shows nothing on the screen. It's black when I set glClearColor to black, and it's white when i set glClearColor to white.

Updated image loading code:

let surface = sdlimage.load("image.png")

if surface.isNil:

  echo "Image couldn't be loaded: ", sdl2.getError()

  quit 1



var w = surface.w # may need to make this the next power of two

var h = surface.h # and this

var bpp: cint

var Rmask, Gmask, Bmask, Amask: uint32

if not pixelFormatEnumToMasks(SDL_PIXELFORMAT_ABGR8888, bpp,

  Rmask, Gmask, Bmask, Amask):

  quit "pixel format enum to masks " & $sdl2.getError()



let newSurface = createRGBSurface(0, w, h, bpp,

  Rmask, Gmask, Bmask, Amask)



discard surface.setSurfaceAlphaMod(0xFF)

discard surface.setSurfaceBlendMode(BlendMode_None)



blitSurface(surface, nil, newSurface, nil)



var tex: cuint

glGenTextures(1, addr tex)

glBindTexture(GL_TEXTURE_2D, tex)

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)

glTexImage2D(GL_TEXTURE_2D, 0, 4, w.GLsizei, h.GLsizei, 0, GL_RGBA, GL_UNSIGNED_BYTE, newSurface.pixels)

Image rendering code:

glUseProgram(shaderProgram)

glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT)

glMatrixMode(GL_MODELVIEW)

glLoadIdentity()

glTranslatef(0.0, 0.0, -7.0)

glColor3f(1.0, 1.0, 1.0)

glBegin(GL_QUADS)

glTexCoord2i(0, 0)

glVertex3f(-0.5, -1.9, 0.0)

glTexCoord2i(1, 0)

glVertex3f(0.5, -1.9, 0.0)

glTexCoord2i(0, 1)

glVertex3f(-0.5, -1.4, 0.0)

glTexCoord2i(1, 1)

glVertex3f(0.5, -1.4, 0.0)

glEnd()

If shaders have something to do with it, here's my vertex shader:

#version 330 core

in vec4 data;

out vec3 ourColor;

void main() {

  gl_Position = vec4(data.x, data.y, data.z, 1.0);

  ourColor = vec3(data.w, data.w, data.w);

}

And the fragment shader:

#version 330 core

precision highp float;

in vec3 ourColor;

out vec4 color;

void main() {

  color = vec4(ourColor, 1.0);

}

You should check glGetError() to see if there are any OpenGL errors occurring. You should also check the surface.pixelFormat to see whether you actually have 4 bytes per pixel in your image. If it's just RGB data and not RGBA, then glTexImage2D() will read past the end of the image data and likely crash with a segmentation fault.