Ive been trying to find out how to resize the window and how to load an image with an alpha channel. Ive looked at heaps of examples, but can't get them to work. When I resize the window I can't draw my textures (they just end up white) any more, even though I have reloaded them. When I get a resize event I call my Renderer class's init() function, I think thats where the problem is:
void Renderer::init(Uint16 w, Uint16 h, Uint8 bpp, Uint32 flags, int projection)
{
// Clear the textures.
m_textures.clear();
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5); // Use at least 5 bits of Red
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5); // Use at least 5 bits of Green
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5); // Use at least 5 bits of Blue
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16); // Use at least 16 bits for the depth buffer
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); // Enable double buffering
// Get video info.
m_info = SDL_GetVideoInfo();
if (m_info == 0)
{
throw RenderException("Couldn't get SDL video info.");
}
m_screen = SDL_SetVideoMode(w, h, bpp, SDL_OPENGL | flags);
if (m_screen == NULL)
{
throw RenderException("Unable to set SDL video mode.");
}
// Set OpenGL states.
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
glClearDepth(1.0f);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
//glHint(GL_FOG_HINT, GL_NICEST);
glEnable(GL_CULL_FACE);
// Set blending.
glBlendFunc(GL_SRC_ALPHA, GL_ONE);
glEnable(GL_BLEND);
// Make textures appear the right way up.
glMatrixMode(GL_TEXTURE);
glRotatef(180.0f, 0.0f, 0.0f, 1.0f);
glScalef(-1.0f, 1.0f, 1.0f);
// Set the OpenGL projection.
setProjection(projection);
}
void Renderer::setProjection(int projection)
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
switch (projection)
{
case RENDERER_PERSPECTIVE:
glDepthFunc(GL_LEQUAL);
glEnable(GL_DEPTH_TEST);
gluPerspective(45.0f, (GLfloat)m_screen->w/(GLfloat)m_screen->h, 0.1f, 100.0f);
break;
case RENDERER_ORTHO:
glDepthFunc(GL_LEQUAL);
glEnable(GL_DEPTH_TEST);
glOrtho(0.0f, m_screen->w, m_screen->h, 0.0f, -1.0f, 1.0f);
break;
}
// Go back to the model view.
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
For loading images with alpha, I am using this (and passing TEXTURE_MIPMAP_ALPHA):
GLuint Texture::load(const ::std::string& fileName, int type)
{
SDL_Surface* temp;
if ((temp = IMG_Load(fileName.c_str())) == 0)
{
report("Unable to load image " + fileName + ".");
return 0;
}
if (temp->w < 1)
{
report("Image width is invalid (< 1).");
SDL_FreeSurface(temp);
return 0;
}
// Enable 2D texturing.
glEnable(GL_TEXTURE_2D);
glGenTextures(1, &m_id);
glBindTexture(GL_TEXTURE_2D, m_id);
switch (type)
{
case TEXTURE_NORMAL:
glTexImage2D(GL_TEXTURE_2D, 0, 3, temp->w, temp->h, 0, GL_BGR,
GL_UNSIGNED_BYTE, temp->pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
break;
case TEXTURE_ALPHA:
glTexImage2D(GL_TEXTURE_2D, 0, 4, temp->w, temp->h, 0, GL_RGBA,
GL_UNSIGNED_BYTE, temp->pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
break;
case TEXTURE_MIPMAP:
gluBuild2DMipmaps(GL_TEXTURE_2D, 3, temp->w, temp->h, GL_BGR,
GL_UNSIGNED_BYTE, temp->pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_NEAREST);
break;
case TEXTURE_MIPMAP_ALPHA:
gluBuild2DMipmaps(GL_TEXTURE_2D, 4, temp->w, temp->h, GL_RGBA,
GL_UNSIGNED_BYTE, temp->pixels);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_NEAREST);
}
SDL_FreeSurface(temp);
return m_id;
}
