render: Flip textures in case of inverted_y

include/wlr/render.h

@@ -85,6 +85,7 @@ struct wlr_texture {
 	bool valid;
 	uint32_t format;
 	int width, height;
+	bool inverted_y;
 	struct wl_signal destroy_signal;
 	struct wl_resource *resource;
 };

render/gles2/renderer.c

@@ -179,7 +179,8 @@ static bool wlr_gles2_render_texture(struct wlr_renderer *wlr_renderer,
 
 	wlr_texture_bind(texture);
 	GL_CALL(glUniformMatrix4fv(0, 1, GL_FALSE, *matrix));
-	GL_CALL(glUniform1f(2, alpha));
+	GL_CALL(glUniform1i(1, texture->inverted_y));
+	GL_CALL(glUniform1f(3, alpha));
 	draw_quad();
 	return true;
 }

render/gles2/shaders.c

@@ -50,6 +50,7 @@ const GLchar ellipse_fragment_src[] =
 // Textured quads
 const GLchar vertex_src[] =
 "uniform mat4 proj;"
+"uniform bool invert_y;"
 "attribute vec2 pos;"
 "attribute vec2 texcoord;"
 "varying vec2 v_texcoord;"
@@ -69,7 +70,11 @@ const GLchar vertex_src[] =
 "}"
 "void main() {"
 "	gl_Position = transpose(proj) * vec4(pos, 0.0, 1.0);"
-"	v_texcoord = texcoord;"
+"  if (invert_y) {"
+"    v_texcoord = vec2(texcoord.s, 1.0 - texcoord.t);"
+"  } else {"
+"    v_texcoord = texcoord;"
+"  }"
 "}";
 
 const GLchar fragment_src_rgba[] =

render/gles2/texture.c

@@ -164,6 +164,7 @@ static bool gles2_texture_upload_drm(struct wlr_texture *_tex,
 
 	EGLint inverted_y;
 	wlr_egl_query_buffer(tex->egl, buf, EGL_WAYLAND_Y_INVERTED_WL, &inverted_y);
+	tex->wlr_texture.inverted_y = !!inverted_y;
 
 	GLenum target;
 	const struct pixel_format *pf;