fix for bug rendering text at small sizes, padding was incorrectly being applied to the characters y offset causing out of bounds pixels to be requested from glTexSubImage2D().

also clamp width, height of the character bitmap to the bitmap bounds since this can still happen for very small text (2-3 pixels high).

1 files changed, 16 insertions, 2 deletions

diff --git a/source/blender/blenfont/intern/blf_glyph.c b/source/blender/blenfont/intern/blf_glyph.c
index 91ecded88be..2c582133b15 100644
--- a/source/blender/blenfont/intern/blf_glyph.c
+++ b/source/blender/blenfont/intern/blf_glyph.c
@@ -383,7 +383,7 @@ int blf_glyph_render(FontBLF *font, GlyphBLF *g, float x, float y)
 		if (gc->cur_tex == -1) {
 			blf_glyph_cache_texture(font, gc);
 			gc->x_offs = gc->pad;
-			gc->y_offs = gc->pad;
+			gc->y_offs = 0;
 		}
 
 		if (gc->x_offs > (gc->p2_width - gc->max_glyph_width)) {
@@ -391,7 +391,7 @@ int blf_glyph_render(FontBLF *font, GlyphBLF *g, float x, float y)
 			gc->y_offs += gc->max_glyph_height;
 
 			if (gc->y_offs > (gc->p2_height - gc->max_glyph_height)) {
-				gc->y_offs = gc->pad;
+				gc->y_offs = 0;
 				blf_glyph_cache_texture(font, gc);
 			}
 		}
@@ -400,6 +400,19 @@ int blf_glyph_render(FontBLF *font, GlyphBLF *g, float x, float y)
 		g->xoff = gc->x_offs;
 		g->yoff = gc->y_offs;
 
+		/* prevent glTexSubImage2D from failing if the character
+		 * asks for pixels out of bounds, this tends only to happen
+		 * with very small sizes (5px high or less) */
+		if (UNLIKELY((g->xoff + g->width)  > gc->p2_width)) {
+			g->width  -= (g->xoff + g->width)  - gc->p2_width;
+			BLI_assert(g->width > 0);
+		}
+		if (UNLIKELY((g->yoff + g->height) > gc->p2_height)) {
+			g->height -= (g->yoff + g->height) - gc->p2_height;
+			BLI_assert(g->height > 0);
+		}
+
+
 		glPushClientAttrib(GL_CLIENT_PIXEL_STORE_BIT);
 		glPixelStorei(GL_UNPACK_LSB_FIRST, GL_FALSE);
 		glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
@@ -407,6 +420,7 @@ int blf_glyph_render(FontBLF *font, GlyphBLF *g, float x, float y)
 
 		glBindTexture(GL_TEXTURE_2D, g->tex);
 		glTexSubImage2D(GL_TEXTURE_2D, 0, g->xoff, g->yoff, g->width, g->height, GL_ALPHA, GL_UNSIGNED_BYTE, g->bitmap);
+		BLI_assert(glGetError() == GL_NO_ERROR);
 		glPopClientAttrib();
 
 		g->uv[0][0] = ((float)g->xoff) / ((float)gc->p2_width);