render/gles2: transpose matrices before binding them

Setting glUniformMatrix3fv's transpose parameter to GL_TRUE is
not allowed for OpenGL ES 2.

This adds a wlr_matrix_transpose function.

include/wlr/types/wlr_matrix.h

@@ -5,11 +5,12 @@
 #include <wlr/types/wlr_box.h>
 
 void wlr_matrix_identity(float mat[static 9]);
+void wlr_matrix_multiply(float mat[static 9], const float a[static 9],
+	const float b[static 9]);
+void wlr_matrix_transpose(float mat[static 9], const float a[static 9]);
 void wlr_matrix_translate(float mat[static 9], float x, float y);
 void wlr_matrix_scale(float mat[static 9], float x, float y);
 void wlr_matrix_rotate(float mat[static 9], float rad);
-void wlr_matrix_multiply(float mat[static 9], const float a[static 9],
-	const float b[static 9]);
 void wlr_matrix_transform(float mat[static 9],
 	enum wl_output_transform transform);
 void wlr_matrix_projection(float mat[static 9], int width, int height,

render/gles2/renderer.c

@@ -180,8 +180,13 @@ static bool wlr_gles2_render_texture_with_matrix(
 		return false;
 	}
 
+	// OpenGL ES 2 requires the glUniformMatrix3fv transpose parameter to be set
+	// to GL_FALSE
+	float transposition[9];
+	wlr_matrix_transpose(transposition, matrix);
+
 	wlr_texture_bind(texture);
-	GL_CALL(glUniformMatrix3fv(0, 1, GL_TRUE, matrix));
+	GL_CALL(glUniformMatrix3fv(0, 1, GL_FALSE, transposition));
 	GL_CALL(glUniform1i(1, texture->inverted_y));
 	GL_CALL(glUniform1f(3, alpha));
 	draw_quad();
@@ -191,16 +196,26 @@ static bool wlr_gles2_render_texture_with_matrix(
 
 static void wlr_gles2_render_quad(struct wlr_renderer *wlr_renderer,
 		const float color[static 4], const float matrix[static 9]) {
+	// OpenGL ES 2 requires the glUniformMatrix3fv transpose parameter to be set
+	// to GL_FALSE
+	float transposition[9];
+	wlr_matrix_transpose(transposition, matrix);
+
 	GL_CALL(glUseProgram(shaders.quad));
-	GL_CALL(glUniformMatrix3fv(0, 1, GL_TRUE, matrix));
+	GL_CALL(glUniformMatrix3fv(0, 1, GL_FALSE, transposition));
 	GL_CALL(glUniform4f(1, color[0], color[1], color[2], color[3]));
 	draw_quad();
 }
 
 static void wlr_gles2_render_ellipse(struct wlr_renderer *wlr_renderer,
 		const float color[static 4], const float matrix[static 9]) {
+	// OpenGL ES 2 requires the glUniformMatrix3fv transpose parameter to be set
+	// to GL_FALSE
+	float transposition[9];
+	wlr_matrix_transpose(transposition, matrix);
+
 	GL_CALL(glUseProgram(shaders.ellipse));
-	GL_CALL(glUniformMatrix3fv(0, 1, GL_TRUE, matrix));
+	GL_CALL(glUniformMatrix3fv(0, 1, GL_FALSE, transposition));
 	GL_CALL(glUniform4f(1, color[0], color[1], color[2], color[3]));
 	draw_quad();
 }

types/wlr_matrix.c

@@ -33,6 +33,15 @@ void wlr_matrix_multiply(float mat[static 9], const float a[static 9],
 	memcpy(mat, product, sizeof(product));
 }
 
+void wlr_matrix_transpose(float mat[static 9], const float a[static 9]) {
+	float transposition[9] = {
+		a[0], a[3], a[6],
+		a[1], a[4], a[7],
+		a[2], a[5], a[8],
+	};
+	memcpy(mat, transposition, sizeof(transposition));
+}
+
 void wlr_matrix_translate(float mat[static 9], float x, float y) {
 	float translate[9] = {
 		1.0f, 0.0f, x,