Fix strobing.

demodir/termgl_demo.c

@@ -129,7 +129,7 @@ void demo_mandelbrot(const unsigned res_x, const unsigned res_y, const unsigned
 {
  TGL *tgl = tgl_init(res_x, res_y, &gradient_full);
  assert(tgl);
- assert(!tgl_enable(tgl, TGL_OUTPUT_BUFFER));
+ assert(!tgl_enable(tgl, TGL_OUTPUT_BUFFER | TGL_PROGRESSIVE));
 
  const unsigned frame_max = 90;
  const unsigned i_max = 255;
@@ -199,7 +199,7 @@ void demo_teapot(const unsigned res_x, const unsigned res_y, const unsigned fram
  assert(tgl);
  assert(!tgl3d_init(tgl));
  tgl3d_cull_face(tgl, TGL_BACK | TGL_CCW);
- assert(!tgl_enable(tgl, TGL_DOUBLE_CHARS | TGL_CULL_FACE | TGL_Z_BUFFER | TGL_OUTPUT_BUFFER));
+ assert(!tgl_enable(tgl, TGL_DOUBLE_CHARS | TGL_CULL_FACE | TGL_Z_BUFFER | TGL_OUTPUT_BUFFER | TGL_PROGRESSIVE));
  tgl3d_camera(tgl, 1.57f, 0.1f, 5.f);
 
  // Load triangles
@@ -291,7 +291,7 @@ void demo_star(const unsigned res_x, const unsigned res_y, const unsigned framet
 {
  TGL *tgl = tgl_init(res_x, res_y, &gradient_min);
  assert(tgl);
- assert(!tgl_enable(tgl, TGL_OUTPUT_BUFFER));
+ assert(!tgl_enable(tgl, TGL_OUTPUT_BUFFER | TGL_PROGRESSIVE));
 
  const float pi2 = 6.28319f;
  const unsigned n = 8, d = 3;
@@ -381,6 +381,7 @@ int main(int argc, char **argv)
  (void)argc;
  (void)argv;
 
+ tgl_clear_screen();
  puts(HELPTEXT_HEADER);
  unsigned col, row;
  tglutil_get_console_size(&col, &row, true);
@@ -389,6 +390,7 @@ int main(int argc, char **argv)
 
  unsigned n = 0;
  assert(scanf("%u", &n) == 1);
+ tgl_clear_screen();
 
  switch (n) {
  case 1u:

lib/termgl.h

@@ -49,8 +49,9 @@ enum {
  TGL_Z_BUFFER = 0x04,
 /* settings */
  TGL_DOUBLE_CHARS = 0x10,
+ TGL_PROGRESSIVE = 0x20,
 #ifdef TERMGL3D
- TGL_CULL_FACE = 0x20,
+ TGL_CULL_FACE = 0x40,
 #endif
 };
 
@@ -93,13 +94,19 @@ int tgl_flush(TGL *tgl);
  */
 void tgl_clear(TGL *tgl, uint8_t buffers);
 
+/**
+ * Clears the screen
+ */
+void tgl_clear_screen(void);
+
 /**
  * Enables or disables certain settings
  * @param settings: bitwise combination of settings:
  * TGL_Z_BUFFER - depth buffer
  * TGL_DOUBLE_CHARS - square pixels by printing 2 characters per pixel
  * TGL_CULL_FACE - (3D ONLY) cull specified triangle faces
  * TGL_OUTPUT_BUFFER - output buffer allowing for just one print to flush. Mush faster on most terminals, but requires a few hundred kilobytes of memory
+ * TGL_PROGRESSIVE - Over-write previous frame. Eliminates strobing but requires call to tgl_clear_screen before drawing smaller image and after resizing terminal if terminal size was smaller than frame size
  * @return 0 on success, -1 on failure
  * On failure, errno is set to value specified by: https://www.man7.org/linux/man-pages/man3/malloc.3.html#ERRORS
  */

src/termgl.c

@@ -9,7 +9,7 @@
 /**
  * Setting MACROs
  */
-#define TGL_CLEAR_SCREEN do {fputs("\033[1;1H\033[2J", stdout);} while (0)
+#define TGL_CLEAR_SCR do {fputs("\033[1;1H\033[2J", stdout);} while (0)
 #define TGL_TYPEOF __typeof__
 #define TGL_MALLOC malloc
 #define TGL_FREE free
@@ -122,6 +122,11 @@ void tgl_clear(TGL * const tgl, const uint8_t buffers)
  memset(tgl->output_buffer, '\0', tgl->output_buffer_size);
 }
 
+void tgl_clear_screen(void)
+{
+ TGL_CLEAR_SCR;
+}
+
 TGL *tgl_init(const unsigned width, const unsigned height, const TGLGradient * gradient)
 {
 #ifdef TGL_OS_WINDOWS
@@ -224,7 +229,11 @@ char *itgl_generate_sgr(const uint16_t color_prev, const uint16_t color_cur, cha
 
 int tgl_flush(TGL * const tgl)
 {
- TGL_CLEAR_SCREEN;
+ if (tgl->settings & TGL_PROGRESSIVE)
+ CALL_STDOUT(fputs("\033[;H", stdout), -1);
+ else
+ TGL_CLEAR_SCR;
+
  uint16_t color = 0x0007;
  unsigned row, col;
  Pixel *pixel = tgl->frame_buffer;