compositor: Move surface repaint code to gles2-renderer.c
diff --git a/src/compositor.c b/src/compositor.c
index c481083..ac78eda 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -479,9 +479,9 @@
 	*y = wl_fixed_from_double(yf);
 }
 
-static void
-surface_from_global_float(struct weston_surface *surface,
-			  GLfloat x, GLfloat y, GLfloat *sx, GLfloat *sy)
+WL_EXPORT void
+weston_surface_from_global_float(struct weston_surface *surface,
+				 GLfloat x, GLfloat y, GLfloat *sx, GLfloat *sy)
 {
 	if (surface->transform.enabled) {
 		struct weston_vector v = { { x, y, 0.0f, 1.0f } };
@@ -512,10 +512,10 @@
 {
 	GLfloat sxf, syf;
 
-	surface_from_global_float(surface,
-	                          wl_fixed_to_double(x),
-				  wl_fixed_to_double(y),
-				  &sxf, &syf);
+	weston_surface_from_global_float(surface,
+					 wl_fixed_to_double(x),
+					 wl_fixed_to_double(y),
+					 &sxf, &syf);
 	*sx = wl_fixed_from_double(sxf);
 	*sy = wl_fixed_from_double(syf);
 }
@@ -526,7 +526,7 @@
 {
 	GLfloat sxf, syf;
 
-	surface_from_global_float(surface, x, y, &sxf, &syf);
+	weston_surface_from_global_float(surface, x, y, &sxf, &syf);
 	*sx = floorf(sxf);
 	*sy = floorf(syf);
 }
@@ -862,551 +862,6 @@
 }
 
 
-#define max(a, b) (((a) > (b)) ? (a) : (b))
-#define min(a, b) (((a) > (b)) ? (b) : (a))
-#define clip(x, a, b)  min(max(x, a), b)
-#define sign(x)   ((x) >= 0)
-
-static int
-calculate_edges(struct weston_surface *es, pixman_box32_t *rect,
-		pixman_box32_t *surf_rect, GLfloat *ex, GLfloat *ey)
-{
-	int i, n = 0;
-	GLfloat min_x, max_x, min_y, max_y;
-	GLfloat x[4] = {
-			surf_rect->x1, surf_rect->x2, surf_rect->x2, surf_rect->x1,
-	};
-	GLfloat y[4] = {
-			surf_rect->y1, surf_rect->y1, surf_rect->y2, surf_rect->y2,
-	};
-	GLfloat cx1 = rect->x1;
-	GLfloat cx2 = rect->x2;
-	GLfloat cy1 = rect->y1;
-	GLfloat cy2 = rect->y2;
-
-	GLfloat dist_squared(GLfloat x1, GLfloat y1, GLfloat x2, GLfloat y2)
-	{
-		GLfloat dx = (x1 - x2);
-		GLfloat dy = (y1 - y2);
-		return dx * dx + dy * dy;
-	}
-
-	void append_vertex(GLfloat x, GLfloat y)
-	{
-		/* don't emit duplicate vertices: */
-		if ((n > 0) && (ex[n-1] == x) && (ey[n-1] == y))
-			return;
-		ex[n] = x;
-		ey[n] = y;
-		n++;
-	}
-
-	/* transform surface to screen space: */
-	for (i = 0; i < 4; i++)
-		weston_surface_to_global_float(es, x[i], y[i], &x[i], &y[i]);
-
-	/* find bounding box: */
-	min_x = max_x = x[0];
-	min_y = max_y = y[0];
-
-	for (i = 1; i < 4; i++) {
-		min_x = min(min_x, x[i]);
-		max_x = max(max_x, x[i]);
-		min_y = min(min_y, y[i]);
-		max_y = max(max_y, y[i]);
-	}
-
-	/* First, simple bounding box check to discard early transformed
-	 * surface rects that do not intersect with the clip region:
-	 */
-	if ((min_x > cx2) || (max_x < cx1) ||
-			(min_y > cy2) || (max_y < cy1))
-		return 0;
-
-	/* Simple case, bounding box edges are parallel to surface edges,
-	 * there will be only four edges.  We just need to clip the surface
-	 * vertices to the clip rect bounds:
-	 */
-	if (!es->transform.enabled) {
-		for (i = 0; i < 4; i++) {
-			ex[n] = clip(x[i], cx1, cx2);
-			ey[n] = clip(y[i], cy1, cy2);
-			n++;
-		}
-		return 4;
-	}
-
-	/* Hard case, transformation applied.  We need to find the vertices
-	 * of the shape that is the intersection of the clip rect and
-	 * transformed surface.  This can be anything from 3 to 8 sides.
-	 *
-	 * Observation: all the resulting vertices will be the intersection
-	 * points of the transformed surface and the clip rect, plus the
-	 * vertices of the clip rect which are enclosed by the transformed
-	 * surface and the vertices of the transformed surface which are
-	 * enclosed by the clip rect.
-	 *
-	 * Observation: there will be zero, one, or two resulting vertices
-	 * for each edge of the src rect.
-	 *
-	 * Loop over four edges of the transformed rect:
-	 */
-	for (i = 0; i < 4; i++) {
-		GLfloat x1, y1, x2, y2;
-		int last_n = n;
-
-		x1 = x[i];
-		y1 = y[i];
-
-		/* if this vertex is contained in the clip rect, use it as-is: */
-		if ((cx1 <= x1) && (x1 <= cx2) &&
-				(cy1 <= y1) && (y1 <= cy2))
-			append_vertex(x1, y1);
-
-		/* for remaining, we consider the point as part of a line: */
-		x2 = x[(i+1) % 4];
-		y2 = y[(i+1) % 4];
-
-		if (x1 == x2) {
-			append_vertex(clip(x1, cx1, cx2), clip(y1, cy1, cy2));
-			append_vertex(clip(x2, cx1, cx2), clip(y2, cy1, cy2));
-		} else if (y1 == y2) {
-			append_vertex(clip(x1, cx1, cx2), clip(y1, cy1, cy2));
-			append_vertex(clip(x2, cx1, cx2), clip(y2, cy1, cy2));
-		} else {
-			GLfloat m, c, p;
-			GLfloat tx[2], ty[2];
-			int tn = 0;
-
-			int intersect_horiz(GLfloat y, GLfloat *p)
-			{
-				GLfloat x;
-
-				/* if y does not lie between y1 and y2, no
-				 * intersection possible
-				 */
-				if (sign(y-y1) == sign(y-y2))
-					return 0;
-
-				x = (y - c) / m;
-
-				/* if x does not lie between cx1 and cx2, no
-				 * intersection:
-				 */
-				if (sign(x-cx1) == sign(x-cx2))
-					return 0;
-
-				*p = x;
-				return 1;
-			}
-
-			int intersect_vert(GLfloat x, GLfloat *p)
-			{
-				GLfloat y;
-
-				if (sign(x-x1) == sign(x-x2))
-					return 0;
-
-				y = m * x + c;
-
-				if (sign(y-cy1) == sign(y-cy2))
-					return 0;
-
-				*p = y;
-				return 1;
-			}
-
-			/* y = mx + c */
-			m = (y2 - y1) / (x2 - x1);
-			c = y1 - m * x1;
-
-			/* check for up to two intersections with the four edges
-			 * of the clip rect.  Note that we don't know the orientation
-			 * of the transformed surface wrt. the clip rect.  So if when
-			 * there are two intersection points, we need to put the one
-			 * closest to x1,y1 first:
-			 */
-
-			/* check top clip rect edge: */
-			if (intersect_horiz(cy1, &p)) {
-				ty[tn] = cy1;
-				tx[tn] = p;
-				tn++;
-			}
-
-			/* check right clip rect edge: */
-			if (intersect_vert(cx2, &p)) {
-				ty[tn] = p;
-				tx[tn] = cx2;
-				tn++;
-				if (tn == 2)
-					goto edge_check_done;
-			}
-
-			/* check bottom clip rect edge: */
-			if (intersect_horiz(cy2, &p)) {
-				ty[tn] = cy2;
-				tx[tn] = p;
-				tn++;
-				if (tn == 2)
-					goto edge_check_done;
-			}
-
-			/* check left clip rect edge: */
-			if (intersect_vert(cx1, &p)) {
-				ty[tn] = p;
-				tx[tn] = cx1;
-				tn++;
-			}
-
-edge_check_done:
-			if (tn == 1) {
-				append_vertex(tx[0], ty[0]);
-			} else if (tn == 2) {
-				if (dist_squared(x1, y1, tx[0], ty[0]) <
-						dist_squared(x1, y1, tx[1], ty[1])) {
-					append_vertex(tx[0], ty[0]);
-					append_vertex(tx[1], ty[1]);
-				} else {
-					append_vertex(tx[1], ty[1]);
-					append_vertex(tx[0], ty[0]);
-				}
-			}
-
-			if (n == last_n) {
-				GLfloat best_x=0, best_y=0;
-				uint32_t d, best_d = (unsigned int)-1; /* distance squared */
-				uint32_t max_d = dist_squared(x2, y2,
-						x[(i+2) % 4], y[(i+2) % 4]);
-
-				/* if there are no vertices on this line, it could be that
-				 * there is a vertex of the clip rect that is enclosed by
-				 * the transformed surface.  Find the vertex of the clip
-				 * rect that is reached by the shortest line perpendicular
-				 * to the current edge, if any.
-				 *
-				 * slope of perpendicular is 1/m, so
-				 *
-				 *   cy = -cx/m + c2
-				 *   c2 = cy + cx/m
-				 *
-				 */
-
-				int perp_intersect(GLfloat cx, GLfloat cy, uint32_t *d)
-				{
-					GLfloat c2 = cy + cx/m;
-					GLfloat x = (c2 - c) / (m + 1/m);
-
-					/* if the x position of the intersection of the
-					 * perpendicular with the transformed edge does
-					 * not lie within the bounds of the edge, then
-					 * no intersection:
-					 */
-					if (sign(x-x1) == sign(x-x2))
-						return 0;
-
-					*d = dist_squared(cx, cy, x, (m * x) + c);
-
-					/* if intersection distance is further away than
-					 * opposite edge of surface region, it is invalid:
-					 */
-					if (*d > max_d)
-						return 0;
-
-					return 1;
-				}
-
-				if (perp_intersect(cx1, cy1, &d)) {
-					best_x = cx1;
-					best_y = cy1;
-					best_d = d;
-				}
-
-				if (perp_intersect(cx1, cy2, &d) && (d < best_d)) {
-					best_x = cx1;
-					best_y = cy2;
-					best_d = d;
-				}
-
-				if (perp_intersect(cx2, cy2, &d) && (d < best_d)) {
-					best_x = cx2;
-					best_y = cy2;
-					best_d = d;
-				}
-
-				if (perp_intersect(cx2, cy1, &d) && (d < best_d)) {
-					best_x = cx2;
-					best_y = cy1;
-					best_d = d;
-				}
-
-				if (best_d != (unsigned int)-1)  // XXX can this happen?
-					append_vertex(best_x, best_y);
-			}
-		}
-
-	}
-
-	return n;
-}
-
-static int
-texture_region(struct weston_surface *es, pixman_region32_t *region,
-		pixman_region32_t *surf_region)
-{
-	struct weston_compositor *ec = es->compositor;
-	GLfloat *v, inv_width, inv_height;
-	unsigned int *vtxcnt, nvtx = 0;
-	pixman_box32_t *rects, *surf_rects;
-	int i, j, k, nrects, nsurf;
-
-	rects = pixman_region32_rectangles(region, &nrects);
-	surf_rects = pixman_region32_rectangles(surf_region, &nsurf);
-
-	/* worst case we can have 8 vertices per rect (ie. clipped into
-	 * an octagon):
-	 */
-	v = wl_array_add(&ec->vertices, nrects * nsurf * 8 * 4 * sizeof *v);
-	vtxcnt = wl_array_add(&ec->vtxcnt, nrects * nsurf * sizeof *vtxcnt);
-
-	inv_width = 1.0 / es->pitch;
-	inv_height = 1.0 / es->geometry.height;
-
-	for (i = 0; i < nrects; i++) {
-		pixman_box32_t *rect = &rects[i];
-		for (j = 0; j < nsurf; j++) {
-			pixman_box32_t *surf_rect = &surf_rects[j];
-			GLfloat sx, sy;
-			GLfloat ex[8], ey[8];          /* edge points in screen space */
-			int n;
-
-			/* The transformed surface, after clipping to the clip region,
-			 * can have as many as eight sides, emitted as a triangle-fan.
-			 * The first vertex in the triangle fan can be chosen arbitrarily,
-			 * since the area is guaranteed to be convex.
-			 *
-			 * If a corner of the transformed surface falls outside of the
-			 * clip region, instead of emitting one vertex for the corner
-			 * of the surface, up to two are emitted for two corresponding
-			 * intersection point(s) between the surface and the clip region.
-			 *
-			 * To do this, we first calculate the (up to eight) points that
-			 * form the intersection of the clip rect and the transformed
-			 * surface.
-			 */
-			n = calculate_edges(es, rect, surf_rect, ex, ey);
-			if (n < 3)
-				continue;
-
-			/* emit edge points: */
-			for (k = 0; k < n; k++) {
-				surface_from_global_float(es, ex[k], ey[k], &sx, &sy);
-				/* position: */
-				*(v++) = ex[k];
-				*(v++) = ey[k];
-				/* texcoord: */
-				*(v++) = sx * inv_width;
-				*(v++) = sy * inv_height;
-			}
-
-			vtxcnt[nvtx++] = n;
-		}
-	}
-
-	return nvtx;
-}
-
-static void
-triangle_fan_debug(struct weston_surface *surface, int first, int count)
-{
-	struct weston_compositor *compositor = surface->compositor;
-	int i;
-	GLushort *buffer;
-	GLushort *index;
-	int nelems;
-	static int color_idx = 0;
-	static const GLfloat color[][4] = {
-			{ 1.0, 0.0, 0.0, 1.0 },
-			{ 0.0, 1.0, 0.0, 1.0 },
-			{ 0.0, 0.0, 1.0, 1.0 },
-			{ 1.0, 1.0, 1.0, 1.0 },
-	};
-
-	nelems = (count - 1 + count - 2) * 2;
-
-	buffer = malloc(sizeof(GLushort) * nelems);
-	index = buffer;
-
-	for (i = 1; i < count; i++) {
-		*index++ = first;
-		*index++ = first + i;
-	}
-
-	for (i = 2; i < count; i++) {
-		*index++ = first + i - 1;
-		*index++ = first + i;
-	}
-
-	glUseProgram(compositor->solid_shader.program);
-	glUniform4fv(compositor->solid_shader.color_uniform, 1,
-			color[color_idx++ % ARRAY_LENGTH(color)]);
-	glDrawElements(GL_LINES, nelems, GL_UNSIGNED_SHORT, buffer);
-	glUseProgram(compositor->current_shader->program);
-	free(buffer);
-}
-
-static void
-repaint_region(struct weston_surface *es, pixman_region32_t *region,
-		pixman_region32_t *surf_region)
-{
-	struct weston_compositor *ec = es->compositor;
-	GLfloat *v;
-	unsigned int *vtxcnt;
-	int i, first, nfans;
-
-	/* The final region to be painted is the intersection of
-	 * 'region' and 'surf_region'. However, 'region' is in the global
-	 * coordinates, and 'surf_region' is in the surface-local
-	 * coordinates. texture_region() will iterate over all pairs of
-	 * rectangles from both regions, compute the intersection
-	 * polygon for each pair, and store it as a triangle fan if
-	 * it has a non-zero area (at least 3 vertices, actually).
-	 */
-	nfans = texture_region(es, region, surf_region);
-
-	v = ec->vertices.data;
-	vtxcnt = ec->vtxcnt.data;
-
-	/* position: */
-	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof *v, &v[0]);
-	glEnableVertexAttribArray(0);
-
-	/* texcoord: */
-	glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof *v, &v[2]);
-	glEnableVertexAttribArray(1);
-
-	for (i = 0, first = 0; i < nfans; i++) {
-		glDrawArrays(GL_TRIANGLE_FAN, first, vtxcnt[i]);
-		if (ec->fan_debug)
-			triangle_fan_debug(es, first, vtxcnt[i]);
-		first += vtxcnt[i];
-	}
-
-	glDisableVertexAttribArray(1);
-	glDisableVertexAttribArray(0);
-
-	ec->vertices.size = 0;
-	ec->vtxcnt.size = 0;
-}
-
-static void
-weston_compositor_use_shader(struct weston_compositor *compositor,
-			     struct weston_shader *shader)
-{
-	if (compositor->current_shader == shader)
-		return;
-
-	glUseProgram(shader->program);
-	compositor->current_shader = shader;
-}
-
-static void
-weston_shader_uniforms(struct weston_shader *shader,
-		       struct weston_surface *surface,
-		       struct weston_output *output)
-{
-	int i;
-
-	glUniformMatrix4fv(shader->proj_uniform,
-			   1, GL_FALSE, output->matrix.d);
-	glUniform4fv(shader->color_uniform, 1, surface->color);
-	glUniform1f(shader->alpha_uniform, surface->alpha);
-
-	for (i = 0; i < surface->num_textures; i++)
-		glUniform1i(shader->tex_uniforms[i], i);
-}
-
-WL_EXPORT void
-weston_surface_draw(struct weston_surface *es, struct weston_output *output,
-		    pixman_region32_t *damage) /* in global coordinates */
-{
-	struct weston_compositor *ec = es->compositor;
-	/* repaint bounding region in global coordinates: */
-	pixman_region32_t repaint;
-	/* non-opaque region in surface coordinates: */
-	pixman_region32_t surface_blend;
-	GLint filter;
-	int i;
-
-	pixman_region32_init(&repaint);
-	pixman_region32_intersect(&repaint,
-				  &es->transform.boundingbox, damage);
-	pixman_region32_subtract(&repaint, &repaint, &es->clip);
-
-	if (!pixman_region32_not_empty(&repaint))
-		goto out;
-
-	pixman_region32_subtract(&ec->primary_plane.damage,
-				 &ec->primary_plane.damage, &repaint);
-
-	glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
-
-	if (ec->fan_debug) {
-		weston_compositor_use_shader(ec, &ec->solid_shader);
-		weston_shader_uniforms(&ec->solid_shader, es, output);
-	}
-
-	weston_compositor_use_shader(ec, es->shader);
-	weston_shader_uniforms(es->shader, es, output);
-
-	if (es->transform.enabled || output->zoom.active)
-		filter = GL_LINEAR;
-	else
-		filter = GL_NEAREST;
-
-	for (i = 0; i < es->num_textures; i++) {
-		glActiveTexture(GL_TEXTURE0 + i);
-		glBindTexture(es->target, es->textures[i]);
-		glTexParameteri(es->target, GL_TEXTURE_MIN_FILTER, filter);
-		glTexParameteri(es->target, GL_TEXTURE_MAG_FILTER, filter);
-	}
-
-	/* blended region is whole surface minus opaque region: */
-	pixman_region32_init_rect(&surface_blend, 0, 0,
-				  es->geometry.width, es->geometry.height);
-	pixman_region32_subtract(&surface_blend, &surface_blend, &es->opaque);
-
-	if (pixman_region32_not_empty(&es->opaque)) {
-		if (es->shader == &ec->texture_shader_rgba) {
-			/* Special case for RGBA textures with possibly
-			 * bad data in alpha channel: use the shader
-			 * that forces texture alpha = 1.0.
-			 * Xwayland surfaces need this.
-			 */
-			weston_compositor_use_shader(ec, &ec->texture_shader_rgbx);
-			weston_shader_uniforms(&ec->texture_shader_rgbx, es, output);
-		}
-
-		if (es->alpha < 1.0)
-			glEnable(GL_BLEND);
-		else
-			glDisable(GL_BLEND);
-
-		repaint_region(es, &repaint, &es->opaque);
-	}
-
-	if (pixman_region32_not_empty(&surface_blend)) {
-		weston_compositor_use_shader(ec, es->shader);
-		glEnable(GL_BLEND);
-		repaint_region(es, &repaint, &surface_blend);
-	}
-
-	pixman_region32_fini(&surface_blend);
-
-out:
-	pixman_region32_fini(&repaint);
-}
-
 WL_EXPORT void
 weston_surface_restack(struct weston_surface *surface, struct wl_list *below)
 {