fix(gles): transpose lv_matrix_t before uploading to shader (#9703)

src/drivers/opengles/lv_opengles_driver.c

@@ -348,11 +348,14 @@ void lv_opengles_render(const lv_opengles_render_params_t * params)
         lv_matrix_scale(&matrix, hor_scale, ver_scale);
     }
 
+    lv_matrix_t gl_matrix;
+    lv_matrix_transpose(&matrix, &gl_matrix);
+
     lv_opengles_shader_bind();
     lv_opengles_enable_blending(params->blend_opt);
     lv_opengles_shader_set_uniform1f("u_ColorDepth", LV_COLOR_DEPTH);
     lv_opengles_shader_set_uniform1i("u_Texture", 0);
-    lv_opengles_shader_set_uniformmatrix3fv("u_VertexTransform", 1, (const float *)&matrix);
+    lv_opengles_shader_set_uniformmatrix3fv("u_VertexTransform", 1, (float *)&gl_matrix);
     lv_opengles_shader_set_uniform1f("u_Opa", (float)params->opa / (float)LV_OPA_100);
     lv_opengles_shader_set_uniform1i("u_IsFill", params->texture == 0);
     lv_opengles_shader_set_uniform3f("u_FillColor", (float)params->fill_color.red / 255.0f,

src/misc/lv_matrix.c

@@ -243,6 +243,41 @@ bool lv_matrix_is_identity_or_translation(const lv_matrix_t * matrix)
             matrix->m[2][2] == 1.0f);
 }
 
+void lv_matrix_transpose(const lv_matrix_t * src, lv_matrix_t * dst)
+{
+    if(src == NULL || dst == NULL) return;
+
+    if(src == dst) {
+        /* In-place transposition: 3 swaps, minimal stack usage */
+        float tmp;
+
+        tmp = dst->m[0][1];
+        dst->m[0][1] = dst->m[1][0];
+        dst->m[1][0] = tmp;
+
+        tmp = dst->m[0][2];
+        dst->m[0][2] = dst->m[2][0];
+        dst->m[2][0] = tmp;
+
+        tmp = dst->m[1][2];
+        dst->m[1][2] = dst->m[2][1];
+        dst->m[2][1] = tmp;
+    }
+    else {
+        dst->m[0][0] = src->m[0][0];
+        dst->m[0][1] = src->m[1][0];
+        dst->m[0][2] = src->m[2][0];
+
+        dst->m[1][0] = src->m[0][1];
+        dst->m[1][1] = src->m[1][1];
+        dst->m[1][2] = src->m[2][1];
+
+        dst->m[2][0] = src->m[0][2];
+        dst->m[2][1] = src->m[1][2];
+        dst->m[2][2] = src->m[2][2];
+    }
+}
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/

src/misc/lv_matrix.h

@@ -123,6 +123,14 @@ bool lv_matrix_is_identity(const lv_matrix_t * matrix);
  */
 bool lv_matrix_is_identity_or_translation(const lv_matrix_t * matrix);
 
+/**
+ * Transpose a matrix.
+ * @param src   pointer to the source matrix. If NULL, the function returns.
+ * @param dst   pointer to the destination matrix. If NULL, the function returns.
+ * Note: src and dst may point to the same matrix for in-place transposition.
+ */
+void lv_matrix_transpose(const lv_matrix_t * src, lv_matrix_t * dst);
+
 /**********************
  *      MACROS
  **********************/