uterm: drm: fix y-inversion bug

OpenGL uses an inverted y-axis by default. However, the old gbm-surface
layer didn't correctly map this. But with the conversion to gbm_surface
objects, we now have the correct OpenGL framebuffers so we have to invert
the y-axis.
This was already fixed for the gltex renderer earlier but we forgot to fix
the uterm-drm blitting backend.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

1 files changed, 7 insertions, 7 deletions

diff --git a/src/uterm_video_drm.c b/src/uterm_video_drm.c
index 2c22543..b5c4d8a 100644
--- a/src/uterm_video_drm.c
+++ b/src/uterm_video_drm.c
@@ -671,18 +671,18 @@ static int display_blend(struct uterm_display *disp,
 	vertices[11] = -1.0;
 
 	texpos[0] = 0.0;
-	texpos[1] = 0.0;
+	texpos[1] = 1.0;
 	texpos[2] = 0.0;
-	texpos[3] = 1.0;
+	texpos[3] = 0.0;
 	texpos[4] = 1.0;
-	texpos[5] = 1.0;
+	texpos[5] = 0.0;
 
 	texpos[6] = 0.0;
-	texpos[7] = 0.0;
+	texpos[7] = 1.0;
 	texpos[8] = 1.0;
-	texpos[9] = 1.0;
+	texpos[9] = 0.0;
 	texpos[10] = 1.0;
-	texpos[11] = 0.0;
+	texpos[11] = 1.0;
 
 	fgcol[0] = fr / 255.0;
 	fgcol[1] = fg / 255.0;
@@ -707,7 +707,7 @@ static int display_blend(struct uterm_display *disp,
 	else
 		height = buf->height;
 
-	glViewport(x, y, width, height);
+	glViewport(x, sh - y - height, width, height);
 	glDisable(GL_BLEND);
 
 	gl_shader_use(disp->video->drm.blend_shader);