Video IP - simple test vga interface

So I found another tutorial online for a similar application but this one uses a NIOS core. I have adapted the tutorial to use on chip memory as opposed to the SRAM they propose. However I still can't get this working!

The tutorial can be found here: https://www.usna.edu/ee/ec463/notes/10_ec463_video_out_student.pdf

Here is my Qsys design (hopefully a high res image) and my C source code. Note I've had to play around with it so that the writing to the onchip memory doesn't go out of bounds and cause the C program to crash.

//Base Addresses from DE2-70 Media Computer with SD# define VGA_PIXEL_BUFFER_BASE_ADR 0x0000000 // SRAM base address# define VGA_BLACK 0x0000 // Black# define VGA_RED 0xF800 // Red# define VGA_WHITE 0xFFFF // Red
# define LED_BASE 0x2000# define SW_BASE 0x2010
/* function prototypes */
    void VGA_box (int, int, int, int, short);
//Main function
int main(void)
{
    int* leds = (int*)LED_BASE; 
    volatile int* sw = (int*)SW_BASE;
    
    /* Create a background frame */
    VGA_box (0, 0, 319, 239, VGA_RED);
    
    /* Create a foreground box */
    VGA_box (30, 30, 90, 90, VGA_WHITE);
    
    /* Create another foreground box */
    VGA_box (50, 50, 70, 70, VGA_RED);
    
    /* main loop */
    while(1) {
        *(leds) = *(sw);
        
        }// hello world
}
/* Draw a filled rectangle on the VGA monitor */
void VGA_box(int x1, int y1, int x2, int y2, short pixel_color)
{
    int offset, row, col;
        volatile int * pixel_buffer = (int *) VGA_PIXEL_BUFFER_BASE_ADR;
        
    while(pixel_buffer < 500){
    
    *(pixel_buffer) = (int) pixel_color;
    pixel_buffer = pixel_buffer + 1;
    }
    /* assume that the box coordinates are valid */
//    for (row = y1; row <= y2; row++)
//    {
//        for (col = x1; col <= x2; col++ )
//        {
//            offset = (row << 9) + col; // compute offset
//            *(pixel_buffer + offset) = (int) pixel_color; // set pixel
//        }
//    }
}

# ###########################EDIT##########################################

I have added an SDRAM controller and SDRAM PLL to my design so that I can store the pixel values in the off chip memory.

My base address for my SDRAM controller is set to 0x08000000 and i have ensured that the video_pixel_buffer_dma has Default buffer start address: 0x08000000 and Default back buffer start address 0x09FFFFFF (half way through the memory).

However I still get a black screen on my VGA output. I believe all my top level connections are correct and that the outputs from the VGA controller can be used without any modification in the top level design entity? As Shown below:

assign VGA_BLANK_N = ~VGA_BLANK;
assign VGA_SYNC_N = ~VGA_SYNC;
 NIOS_VGA_example u0 (
	  .clk_clk       (CLOCK_50),       //   clk.clk
	  .reset_reset_n (KEY), // reset.reset_n
	  .vga_CLK       (VGA_CLK),       //   vga.CLK
	  .vga_HS        (VGA_HS),        //      .HS
	  .vga_VS        (VGA_VS),        //      .VS
	  .vga_BLANK     (VGA_BLANK),     //      .BLANK
	  .vga_SYNC      (VGA_SYNC),      //      .SYNC
	  .vga_R         (VGA_R),         //      .R
	  .vga_G         (VGA_G),         //      .G
	  .vga_B         (VGA_B),          //      .B
	  .switches_export (SW), // switches.export
	  .leds_export     (LEDR),      //     leds.export
	  
	  .sdram_clock_clk  (DRAM_CLK),  // sdram_clock.clk
	  .sdram_wire_addr  (DRAM_ADDR),  //  sdram_wire.addr
	  .sdram_wire_ba    (DRAM_BA),    //            .ba
	  .sdram_wire_cas_n (DRAM_CAS_N), //            .cas_n
	  .sdram_wire_cke   (DRAM_CKE),   //            .cke
	  .sdram_wire_cs_n  (DRAM_CS_N),  //            .cs_n
	  .sdram_wire_dq    (DRAM_DQ),    //            .dq
	  .sdram_wire_dqm   ({DRAM_UDQM, DRAM_LDQM}),   //            .dqm
	  .sdram_wire_ras_n (DRAM_RAS_N), //            .ras_n
	  .sdram_wire_we_n  (DRAM_WE_N)   //            .we_n
  
 );

And due to using the off chip memory I have now use the draw box function written below:

/* Draw a filled rectangle on the VGA monitor */
void VGA_box(int x1, int y1, int x2, int y2, short pixel_color)
{
	int offset, row, col;
		volatile int * pixel_buffer = (int *) VGA_PIXEL_BUFFER_BASE_ADR;
		
//	while(pixel_buffer < 500){
//	
//	*(pixel_buffer) = (int) pixel_color;
//	pixel_buffer = pixel_buffer + 1;
//	}
	/* assume that the box coordinates are valid */
	for (row = y1; row <= y2; row++)
	{
		for (col = x1; col <= x2; col++ )
		{
			offset = (row << 9) + col; // compute offset
			*(pixel_buffer + offset) = (int) pixel_color; // set pixel
		}
	}
}

So this is now as per the original tutorial. However I am definitely missing something here! Does anyone know what?