Drawing sprite on top of a Tile Map - c++

Question

So I have a 2D array which acts as a map for my tiles to be drawn.
int sMap[12][20] = {
{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
{1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1},
{1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1},
{1, 0, 1, 0, 1, 2, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1},
{1, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1},
{1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},
{1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1},
{1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 0, 1},
{1, 1, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 1, 0, 1, 1, 2, 2, 2, 1},
{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1},
{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},
{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
};
Once my tiles have been loaded in, I use this function() to place the tiles:
for (int y = 0; y < 12; y++){
for (int x = 0; x < 20; x++){
if (sMap[y][x] == 1)
glBindTexture( GL_TEXTURE_2D, brick1);
else if (sMap[y][x] == 2)
glBindTexture( GL_TEXTURE_2D, brick2);
else
glBindTexture( GL_TEXTURE_2D, wall );
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f); glVertex3f(float(x + offsetx), float(MAP_SIZEY - (y + offsety)), 0.0f);
glTexCoord2f(1.0f, 0.0f); glVertex3f(float(x + 1 + offsetx), float(MAP_SIZEY - (y + offsety)), 0.0f);
glTexCoord2f(1.0f, 1.0f); glVertex3f(float(x + 1 + offsetx), float(MAP_SIZEY - (y + 1 + offsety)), 0.0f);
glTexCoord2f(0.0f, 1.0f); glVertex3f(float(x + offsetx), float(MAP_SIZEY - (y + 1 + offsety)), 0.0f);
glEnd();
}
}
I think I may have confused myself with the coordinate system of the tiles because when I draw a basic OpenGL square which acts as a sprite, I just get a black screen upon running the program.
I'm unsure whether this means the scale of the sprite to the tiles is wrong, or whether the sprite and tiles are on different Zplanes...
I would appreciate if someone could explain the coordinate system in case I don't understand it as much as I thought and also advise me how to draw an OpenGLsquare on the same coordinates.
Currently I have this to draw my basic sprite:
struct RECT{float x, y, w, h;};
RECT sprite = {0, 0, 10, 10};
void drawSprite (RECT rect){
glBegin(GL_QUADS);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex3f(rect.x, rect.y, 0.0);
glVertex3f(rect.x, rect.y+rect.h, 0.0);
glVertex3f(rect.x+rect.w, rect.y+rect.h, 0.0);
glVertex3f(rect.x+rect.w, rect.y, 0.0);
glEnd();
}
EDIT:
resize screen:
glViewport(0,0,width,height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,20.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
draw scene:
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
gluLookAt(10.0f, 8.0f, 20.0f, 10.0f, 8.0f, 0.0f, 0.0f, 1.0f, 0.0f);
glTranslatef(5.0f,4.0f,0.0f);
draw_tiles();
draw_sprite();

Answer 1

In the draw_tiles function it looks like you might be passing incorrect coordinates - maybe you should be multiplying the x and y values by your tile size.
Also try turning off depth testing and backface culling to help resolve your black screen problem.
glDisable( GL_DEPTH_TEST );
glDisable( GL_CULL_FACE );