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/*
ssd1306_glut.c
Copyright 2014 Doug Szumski <d.s.szumski@gmail.com>
Based on the hd44780 part:
Copyright Luki <humbell@ethz.ch>
Copyright 2011 Michel Pollet <buserror@gmail.com>
This file is part of simavr.
simavr is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
simavr is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with simavr. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "ssd1306_glut.h"
#if __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
ssd1306_colour_t oled_colour_g;
float pix_size_g = 1.0;
float pix_gap_g = 0.0;
// Keep colours in sync with enum in header.
float ssd1306_colours[][3] =
{
{ 1.0f, 1.0f, 1.0f }, // White
{ 0.5f, 0.9f, 1.0f }, // Blue
};
void
ssd1306_gl_init (float pix_size, ssd1306_colour_t oled_colour)
{
pix_size_g = pix_size;
oled_colour_g = oled_colour;
}
void
ssd1306_gl_set_colour (uint8_t invert, float opacity)
{
if (invert)
{
glColor4f (ssd1306_colours[oled_colour_g][0],
ssd1306_colours[oled_colour_g][1],
ssd1306_colours[oled_colour_g][2],
opacity);
} else
{
glColor4f (0.0f, 0.0f, 0.0f, 1.0f);
}
}
float
ssd1306_gl_get_pixel_opacity (uint8_t contrast)
{
// Typically the screen will be clearly visible even at 0 contrast
return contrast / 512.0 + 0.5;
}
uint8_t
ssd1306_gl_reverse_byte (uint8_t byte)
{
byte = (byte & 0xF0) >> 4 | (byte & 0x0F) << 4;
byte = (byte & 0xCC) >> 2 | (byte & 0x33) << 2;
byte = (byte & 0xAA) >> 1 | (byte & 0x55) << 1;
return byte;
}
void
ssd1306_gl_put_pixel_column (uint8_t block_pixel_column, float pixel_opacity,
int invert)
{
glEnable (GL_BLEND);
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glBegin (GL_QUADS);
ssd1306_gl_set_colour (!invert, pixel_opacity);
for (int i = 0; i < 8; ++i)
{
if (block_pixel_column & (1 << i))
{
glVertex2f (pix_size_g, pix_size_g * (i + 1));
glVertex2f (0, pix_size_g * (i + 1));
glVertex2f (0, pix_size_g * i);
glVertex2f (pix_size_g, pix_size_g * i);
}
}
glEnd ();
}
/*
* Controls the mapping between the VRAM and the display.
*/
static uint8_t
ssd1306_gl_get_vram_byte (ssd1306_t *part, uint8_t page, uint8_t column)
{
return part->vram[page][column];
}
static void
ssd1306_gl_draw_pixels (ssd1306_t *part, float opacity, uint8_t invert)
{
for (int p = 0; p < part->pages; p++)
{
glPushMatrix ();
for (int c = 0; c < part->columns; c++)
{
uint8_t vram_byte = ssd1306_gl_get_vram_byte (part, p, c);
ssd1306_gl_put_pixel_column (vram_byte, opacity, invert);
// Next column
glTranslatef (pix_size_g + pix_gap_g, 0, 0);
}
glPopMatrix ();
// Next page
glTranslatef (0,
(part->rows / part->pages) * pix_size_g + pix_gap_g,
0);
}
}
void
ssd1306_gl_draw (ssd1306_t *part)
{
ssd1306_set_flag (part, SSD1306_FLAG_DIRTY, 0);
glEnable (GL_BLEND);
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
// Draw background
float opacity = ssd1306_gl_get_pixel_opacity (part->contrast_register);
int invert = ssd1306_get_flag (part, SSD1306_FLAG_DISPLAY_INVERTED);
ssd1306_gl_set_colour (invert, opacity);
glTranslatef (0, 0, 0);
glBegin (GL_QUADS);
glVertex2f (0, part->rows*pix_size_g);
glVertex2f (0, 0);
glVertex2f (part->columns*pix_size_g, 0);
glVertex2f (part->columns*pix_size_g, part->rows*pix_size_g);
glEnd ();
// Draw pixels
if (ssd1306_get_flag (part, SSD1306_FLAG_DISPLAY_ON))
{
ssd1306_gl_draw_pixels (part, opacity, invert);
}
}
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