Added tests for the vertex clipping code.

This tests (via the table-driven testing method) that the correct
number of vertices and also the correct vertices themselves
are generated for an clip box and polygon of up to eight vertices.

Also add a libshared-test.la so that we don't have to build weston-test-runner
all the time

tests/Makefile.am

@@ -1,7 +1,8 @@
 TESTS = $(shared_tests) $(module_tests) $(weston_tests)
 
 shared_tests = \
-	config-parser.test
+	config-parser.test		\
+	vertex-clip.test
 
 module_tests =				\
 	surface-test.la			\
@@ -48,13 +49,6 @@ AM_CPPFLAGS =					\
 	-DUNIT_TEST				\
 	$(COMPOSITOR_CFLAGS)
 
-
-config_parser_test_LDADD =	\
-	../shared/libshared.la	\
-	$(COMPOSITOR_LIBS)
-config_parser_test_SOURCES =	\
-	config-parser-test.c
-
 surface_global_test_la_SOURCES = surface-global-test.c
 surface_global_test_la_LDFLAGS = -module -avoid-version -rpath $(libdir)
 surface_test_la_SOURCES = surface-test.c
@@ -72,17 +66,38 @@ weston_test_la_SOURCES =		\
 weston_test_runner_src =		\
 	weston-test-runner.c		\
 	weston-test-runner.h
+
+check_LTLIBRARIES = libshared-test.la
+
+libshared_test_la_SOURCES =	\
+	$(weston_test_runner_src)
+libshared_test_la_CFLAGS = $(GCC_CFLAGS) $(COMPOSITOR_CFLAGS)
+
+config_parser_test_LDADD =	\
+	../shared/libshared.la	\
+	libshared-test.la	\
+	$(COMPOSITOR_LIBS)
+config_parser_test_SOURCES =	\
+	config-parser-test.c
+vertex_clip_test_SOURCES =		\
+	vertex-clip-test.c		\
+	../src/vertex-clipping.c	\
+	../src/vertex-clipping.h
+vertex_clip_test_LDADD =	\
+	libshared-test.la	\
+	-lm -lrt
+
 weston_test_client_src =		\
 	weston-test-client-helper.c	\
 	weston-test-client-helper.h	\
 	wayland-test-protocol.c		\
 	wayland-test-client-protocol.h	\
 	subsurface-protocol.c		\
-	subsurface-client-protocol.h	\
+	subsurface-client-protocol.h
-	$(weston_test_runner_src)
 weston_test_client_libs =		\
 	$(SIMPLE_CLIENT_LIBS)		\
-	../shared/libshared.la
+	../shared/libshared.la		\
+	libshared-test.la
 
 keyboard_weston_SOURCES = keyboard-test.c $(weston_test_client_src)
 keyboard_weston_LDADD = $(weston_test_client_libs)

tests/vertex-clip-test.c

@@ -0,0 +1,219 @@
+/*
+ * Copyright © 2013 Sam Spilsbury <smspillaz@gmail.com>
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+#include "weston-test-runner.h"
+
+#include "../src/vertex-clipping.h"
+
+#define BOUNDING_BOX_TOP_Y 100.0f
+#define BOUNDING_BOX_LEFT_X 50.0f
+#define BOUNDING_BOX_RIGHT_X 100.0f
+#define BOUNDING_BOX_BOTTOM_Y 50.0f
+
+#define INSIDE_X1 (BOUNDING_BOX_LEFT_X + 1.0f)
+#define INSIDE_X2 (BOUNDING_BOX_RIGHT_X - 1.0f)
+#define INSIDE_Y1 (BOUNDING_BOX_BOTTOM_Y + 1.0f)
+#define INSIDE_Y2 (BOUNDING_BOX_TOP_Y - 1.0f)
+
+#define OUTSIDE_X1 (BOUNDING_BOX_LEFT_X - 1.0f)
+#define OUTSIDE_X2 (BOUNDING_BOX_RIGHT_X + 1.0f)
+#define OUTSIDE_Y1 (BOUNDING_BOX_BOTTOM_Y - 1.0f)
+#define OUTSIDE_Y2 (BOUNDING_BOX_TOP_Y + 1.0f)
+
+static void
+populate_clip_context (struct clip_context *ctx)
+{
+	ctx->clip.x1 = BOUNDING_BOX_LEFT_X;
+	ctx->clip.y1 = BOUNDING_BOX_BOTTOM_Y;
+	ctx->clip.x2 = BOUNDING_BOX_RIGHT_X;
+	ctx->clip.y2 = BOUNDING_BOX_TOP_Y;
+}
+
+static int
+clip_polygon (struct clip_context *ctx,
+	      struct polygon8 *polygon,
+	      GLfloat *vertices_x,
+	      GLfloat *vertices_y)
+{
+	populate_clip_context(ctx);
+	return clip_transformed(ctx, polygon, vertices_x, vertices_y);
+}
+
+struct vertex_clip_test_data
+{
+	struct polygon8 surface;
+	struct polygon8 expected;
+};
+
+const struct vertex_clip_test_data test_data[] =
+{
+	/* All inside */
+	{
+		{
+			{ INSIDE_X1, INSIDE_X2, INSIDE_X2, INSIDE_X1 },
+			{ INSIDE_Y1, INSIDE_Y1, INSIDE_Y2, INSIDE_Y2 },
+			4
+		},
+		{
+			{ INSIDE_X1, INSIDE_X2, INSIDE_X2, INSIDE_X1 },
+			{ INSIDE_Y1, INSIDE_Y1, INSIDE_Y2, INSIDE_Y2 },
+			4
+		}
+	},
+	/* Top outside */
+	{
+		{
+			{ INSIDE_X1, INSIDE_X2, INSIDE_X2, INSIDE_X1 },
+			{ INSIDE_Y1, INSIDE_Y1, OUTSIDE_Y2, OUTSIDE_Y2 },
+			4
+		},
+		{
+			{ INSIDE_X1, INSIDE_X1, INSIDE_X2, INSIDE_X2 },
+			{ BOUNDING_BOX_TOP_Y, INSIDE_Y1, INSIDE_Y1, BOUNDING_BOX_TOP_Y },
+			4
+		}
+	},
+	/* Bottom outside */
+	{
+		{
+			{ INSIDE_X1, INSIDE_X2, INSIDE_X2, INSIDE_X1 },
+			{ OUTSIDE_Y1, OUTSIDE_Y1, INSIDE_Y2, INSIDE_Y2 },
+			4
+		},
+		{
+			{ INSIDE_X1, INSIDE_X2, INSIDE_X2, INSIDE_X1 },
+			{ BOUNDING_BOX_BOTTOM_Y, BOUNDING_BOX_BOTTOM_Y, INSIDE_Y2, INSIDE_Y2 },
+			4
+		}
+	},
+	/* Left outside */
+	{
+		{
+			{ OUTSIDE_X1, INSIDE_X2, INSIDE_X2, OUTSIDE_X1 },
+			{ INSIDE_Y1, INSIDE_Y1, INSIDE_Y2, INSIDE_Y2 },
+			4
+		},
+		{
+			{ BOUNDING_BOX_LEFT_X, INSIDE_X2, INSIDE_X2, BOUNDING_BOX_LEFT_X },
+			{ INSIDE_Y1, INSIDE_Y1, INSIDE_Y2, INSIDE_Y2 },
+			4
+		}
+	},
+	/* Right outside */
+	{
+		{
+			{ INSIDE_X1, OUTSIDE_X2, OUTSIDE_X2, INSIDE_X1 },
+			{ INSIDE_Y1, INSIDE_Y1, INSIDE_Y2, INSIDE_Y2 },
+			4
+		},
+		{
+			{ INSIDE_X1, BOUNDING_BOX_RIGHT_X, BOUNDING_BOX_RIGHT_X, INSIDE_X1 },
+			{ INSIDE_Y1, INSIDE_Y1, INSIDE_Y2, INSIDE_Y2 },
+			4
+		}
+	},
+	/* Diamond extending from bounding box edges, clip to bounding box */
+	{
+		{
+			{ BOUNDING_BOX_LEFT_X - 25, BOUNDING_BOX_LEFT_X + 25, BOUNDING_BOX_RIGHT_X + 25, BOUNDING_BOX_RIGHT_X - 25 },
+			{ BOUNDING_BOX_BOTTOM_Y + 25, BOUNDING_BOX_TOP_Y + 25, BOUNDING_BOX_TOP_Y - 25, BOUNDING_BOX_BOTTOM_Y - 25 },
+			4
+		},
+		{
+			{ BOUNDING_BOX_LEFT_X, BOUNDING_BOX_LEFT_X, BOUNDING_BOX_RIGHT_X, BOUNDING_BOX_RIGHT_X },
+			{ BOUNDING_BOX_BOTTOM_Y, BOUNDING_BOX_TOP_Y, BOUNDING_BOX_TOP_Y, BOUNDING_BOX_BOTTOM_Y },
+			4
+		}
+	},
+	/* Diamond inside of bounding box edges, clip t bounding box, 8 resulting vertices */
+	{
+		{
+			{ BOUNDING_BOX_LEFT_X - 12.5, BOUNDING_BOX_LEFT_X + 25, BOUNDING_BOX_RIGHT_X + 12.5, BOUNDING_BOX_RIGHT_X - 25 },
+			{ BOUNDING_BOX_BOTTOM_Y + 25, BOUNDING_BOX_TOP_Y + 12.5, BOUNDING_BOX_TOP_Y - 25, BOUNDING_BOX_BOTTOM_Y - 12.5 },
+			4
+		},
+		{
+			{ BOUNDING_BOX_LEFT_X + 12.5, BOUNDING_BOX_LEFT_X, BOUNDING_BOX_LEFT_X, BOUNDING_BOX_LEFT_X + 12.5,
+			  BOUNDING_BOX_RIGHT_X - 12.5, BOUNDING_BOX_RIGHT_X, BOUNDING_BOX_RIGHT_X, BOUNDING_BOX_RIGHT_X - 12.5 },
+			{ BOUNDING_BOX_BOTTOM_Y, BOUNDING_BOX_BOTTOM_Y + 12.5, BOUNDING_BOX_TOP_Y - 12.5, BOUNDING_BOX_TOP_Y,
+			  BOUNDING_BOX_TOP_Y, BOUNDING_BOX_TOP_Y - 12.5, BOUNDING_BOX_BOTTOM_Y + 12.5, BOUNDING_BOX_BOTTOM_Y },
+			8
+		}
+	}
+};
+
+/* clip_polygon modifies the source operand and the test data must
+ * be const, so we need to deep copy it */
+static void
+deep_copy_polygon8(const struct polygon8 *src, struct polygon8 *dst)
+{
+	dst->n = src->n;
+	memcpy((void *) dst->x, src->x, sizeof (src->x));
+	memcpy((void *) dst->y, src->y, sizeof (src->y));
+}
+
+TEST_P(clip_polygon_n_vertices_emitted, test_data)
+{
+	struct vertex_clip_test_data *tdata = data;
+	struct clip_context ctx;
+	struct polygon8 polygon;
+	GLfloat vertices_x[8];
+	GLfloat vertices_y[8];
+	deep_copy_polygon8(&tdata->surface, &polygon);
+	int emitted = clip_polygon(&ctx, &polygon, vertices_x, vertices_y);
+
+	assert(emitted == tdata->expected.n);
+}
+
+TEST_P(clip_polygon_expected_vertices, test_data)
+{
+	struct vertex_clip_test_data *tdata = data;
+	struct clip_context ctx;
+	struct polygon8 polygon;
+	GLfloat vertices_x[8];
+	GLfloat vertices_y[8];
+	deep_copy_polygon8(&tdata->surface, &polygon);
+	int emitted = clip_polygon(&ctx, &polygon, vertices_x, vertices_y);
+	int i = 0;
+
+	for (; i < emitted; ++i)
+	{
+		assert(vertices_x[i] == tdata->expected.x[i]);
+		assert(vertices_y[i] == tdata->expected.y[i]);
+	}
+}
+
+TEST(float_difference_different)
+{
+	assert(float_difference(1.0f, 0.0f) == 1.0f);
+}
+
+TEST(float_difference_same)
+{
+	assert(float_difference(1.0f, 1.0f) == 0.0f);
+}
+