From d7c64d7e566bf4a1ed7a6a6f2bbd28714307f79a Mon Sep 17 00:00:00 2001
From: "K. Lange" <klange@toaruos.org>
Date: Thu, 30 Mar 2023 14:52:26 +0900
Subject: [PATCH] graphics: support shear operation on transformation matrices

---
 base/usr/include/toaru/graphics.h | 1 +
 lib/graphics.c                    | 7 +++++++
 lib/kuroko/_yutani2.c             | 8 ++++++++
 3 files changed, 16 insertions(+)

diff --git a/base/usr/include/toaru/graphics.h b/base/usr/include/toaru/graphics.h
index 4f6275b5..afce2f93 100644
--- a/base/usr/include/toaru/graphics.h
+++ b/base/usr/include/toaru/graphics.h
@@ -133,6 +133,7 @@ extern void gfx_matrix_identity(gfx_matrix_t);
 extern void gfx_matrix_scale(gfx_matrix_t, double x, double y);
 extern void gfx_matrix_translate(gfx_matrix_t, double x, double y);
 extern void gfx_matrix_rotate(gfx_matrix_t, double rotation);
+extern void gfx_matrix_shear(gfx_matrix_t matrix, double x, double y);
 extern void gfx_apply_matrix(double x, double y, gfx_matrix_t matrix, double *out_x, double *out_y);
 
 
diff --git a/lib/graphics.c b/lib/graphics.c
index 5619ff4d..345b010e 100644
--- a/lib/graphics.c
+++ b/lib/graphics.c
@@ -896,6 +896,13 @@ void gfx_matrix_scale(gfx_matrix_t matrix, double x, double y) {
 	});
 }
 
+void gfx_matrix_shear(gfx_matrix_t matrix, double x, double y) {
+	multiply_matrix(matrix, (gfx_matrix_t){
+		{1.0, x, 0.0},
+		{y, 1.0, 0.0},
+	});
+}
+
 void gfx_matrix_rotate(gfx_matrix_t matrix, double r) {
 	multiply_matrix(matrix, (gfx_matrix_t){
 		{ cos(r), -sin(r), 0.0},
diff --git a/lib/kuroko/_yutani2.c b/lib/kuroko/_yutani2.c
index 097b7a8e..c5ee38f2 100644
--- a/lib/kuroko/_yutani2.c
+++ b/lib/kuroko/_yutani2.c
@@ -903,6 +903,13 @@ KRK_Method(TransformMatrix,rotate) {
 	return NONE_VAL();
 }
 
+KRK_Method(TransformMatrix,shear) {
+	double x, y;
+	if (!krk_parseArgs(".dd", (const char*[]){"x","y"}, &x, &y)) return NONE_VAL();
+	gfx_matrix_shear(self->matrix,x,y);
+	return NONE_VAL();
+}
+
 KRK_Method(TransformMatrix,apply) {
 	double x, y;
 	if (!krk_parseArgs(".dd", (const char*[]){"x","y"}, &x, &y)) return NONE_VAL();
@@ -2113,6 +2120,7 @@ KrkValue krk_module_onload__yutani2(void) {
 	BIND_METHOD(TransformMatrix,scale);
 	BIND_METHOD(TransformMatrix,translate);
 	BIND_METHOD(TransformMatrix,rotate);
+	BIND_METHOD(TransformMatrix,shear);
 	BIND_METHOD(TransformMatrix,apply);
 	krk_finalizeClass(TransformMatrix);